I have been studying Arabic for about 6 or 7 years. I have been studying Esperanto for almost 1 month now. Yet, my Esperanto fluency is starting to surpass my Arabic fluency. Imagine if you study Esperanto for several years. I think that if I keep up with this rate, I will be proficient in about a year or so. It doesn't mean that it is easy but it is probably the easiest (all things being relative).

They say that the first foreign language that you learn is the hardest. Also, latin based languages are probably much easier for an English speaker to learn compared to exotic languages like Arabic. That might have a lot to do with it.

Beauty -and in our case: difficulty- is in the eye of the beholder.

Arabic is exotic for you and I guess English is also exotic for an Arab.

Without doubt, it is generally easier to learn a language which is closer to your mother tongue than a language which is from a completely different family. If your maternal language is an indoeuropean one, almost nothing about Esperanto will seem really strange or hard to understand, because -although it is constructed- Esperanto is an indoeuropean language, too. This gives Europeans[1] a certain head-start over people from other linguistic backgrounds when learning Esperanto.

When your maternal language is not indoeuropean, I am nevertheless convinced that Esperanto will be the most easily learned indoeuropean language. But maybe harder to learn than a language closely related to your own.

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[1] Maybe with the exception of those europeans who don't speak an indoeuropean language.

Esperanto can't be called Indo-European, because it is not clear, what "Indo-European" should mean in this case.
The lexicon is taken from romanic, germanic, slavic languages and Greek, so it is European (and neglects the other branches of Indo-European). So are the pragmatics.
But a language is rather defined by its morphology (otherwise many Pidgins/Creols or e.g. Tagalog should be called Indo-European), and the morphology of Esperanto is a mixture of isolating, agglutinating and (a few) fusional elements, while ancient Indo-European is heavily fusional (which makes it nearly unique from a typological POV), and modern Indo-European languages diverge typologically, with most of them being still fusional (but with less inflection).
The article la in Esperanto is a 1:1-calque from Hebrew (ha), by the way.

nornen:If your maternal language is an indoeuropean one, almost nothing about Esperanto will seem really strange or hard to understand, because -although it is constructed- Esperanto is an indoeuropean language, too. This gives Europeans[1] a certain head-start over people from other linguistic backgrounds when learning Esperanto.

The late Claude Piron wrote a paper, "Esperanto: european or asiatic language?", in which he discussed the question of whether Esperanto truly is a fully European (i.e., Indo-European) language. See also his paper, "Esperanto, a western language?".

Kirilo81:Esperanto can't be called Indo-European, because it is not clear, what "Indo-European" should mean in this case.
The lexicon is taken from romanic, germanic, slavic languages and Greek, so it is European (and neglects the other branches of Indo-European). So are the pragmatics.
But a language is rather defined by its morphology (otherwise many Pidgins/Creols or e.g. Tagalog should be called Indo-European), and the morphology of Esperanto is a mixture of isolating, agglutinating and (a few) fusional elements, while ancient Indo-European is heavily fusional (which makes it nearly unique from a typological POV), and modern Indo-European languages diverge typologically, with most of them being still fusional (but with less inflection).
The article la in Esperanto is a 1:1-calque from Hebrew (ha), by the way.

You are right. Let me try to rephrase:

Many aspects of Esperanto are commonly known in other European languages. Among them: nominative-accusative morphsyntactic alignment, dependent marking, inflectional plural, agreement (!), oblique case for direction, participles, infinitives, usage of transitive verbs without direct object ("silent" anti-passive), decimal number system, relative pronouns and gapping relative clauses, prepositions (vs. e.g. postposition).

Those features might not be usual or known in other languages.

For instance, the 16-rules grammar should be sufficient to get a German, English or Russian speaker started with Esperanto. Not so, if your mother tongue doesn't know e.g. participles: in this case, the rules 6f) - 6i) don't explain anything. Or rule 2) if your language has another morphosyntactic alignment. Or $6 of the Ekzercaro "Jen estas la pomo, kiun mi trovis."; if you don't know relative pronouns the word "kiu" is a real puzzler.

nornen:
You are right. Let me try to rephrase:

Many aspects of Esperanto are commonly known in other European languages. Among them: nominative-accusative morphsyntactic alignment, dependent marking, inflectional plural, agreement (!), oblique case for direction, participles, infinitives, usage of transitive verbs without direct object ("silent" anti-passive), decimal number system, relative pronouns and gapping relative clauses, prepositions (vs. e.g. postposition).

N/A alignment, dependent marking, inflectional plural, agreement, infinitives and decimal number system are all used in the Bantu languages, Georgian, Turkish, Semetic languages, Finnish.
Finnish has participles and prepositions as well. So does Georgian. Turkish and Semetic languages have prepositions (not sure about participls for these two families).
The polynesian family has n/a alignment, dependent marking, inflectional plural (albeit via a separate word but still), decimal number system, and prepositions.
None of these features can be characterized as "(indo)european" in the strictest sense.

orthohawk:

nornen:
You are right. Let me try to rephrase:

Many aspects of Esperanto are commonly known in other European languages. Among them: nominative-accusative morphsyntactic alignment, dependent marking, inflectional plural, agreement (!), oblique case for direction, participles, infinitives, usage of transitive verbs without direct object ("silent" anti-passive), decimal number system, relative pronouns and gapping relative clauses, prepositions (vs. e.g. postposition).

N/A alignment, dependent marking, inflectional plural, agreement, infinitives and decimal number system are all used in the Bantu languages, Georgian, Turkish, Semetic languages, Finnish.
Finnish has participles and prepositions as well. So does Georgian. Turkish and Semetic languages have prepositions (not sure about participls for these two families).
The polynesian family has n/a alignment, dependent marking, inflectional plural (albeit via a separate word but still), decimal number system, and prepositions.
None of these features can be characterized as "(indo)european" in the strictest sense.

I wasn't saying that other language will necessarily lack these traits, but that they might lack them.
Nor did I claim these traits to be exclusively indoeuropean.
So I don't quite understand your answer.

nornen:Those features might not be usual or known in other languages.

Bottom line: If you were an alien linguist from Kashyyyk, there is a high probability that you would be able to trace Esperanto back to its european roots (without even considering the lexicon/vocabulary).

nornen:

orthohawk:

nornen:
You are right. Let me try to rephrase:

Many aspects of Esperanto are commonly known in other European languages. Among them: nominative-accusative morphsyntactic alignment, dependent marking, inflectional plural, agreement (!), oblique case for direction, participles, infinitives, usage of transitive verbs without direct object ("silent" anti-passive), decimal number system, relative pronouns and gapping relative clauses, prepositions (vs. e.g. postposition).

N/A alignment, dependent marking, inflectional plural, agreement, infinitives and decimal number system are all used in the Bantu languages, Georgian, Turkish, Semetic languages, Finnish.
Finnish has participles and prepositions as well. So does Georgian. Turkish and Semetic languages have prepositions (not sure about participls for these two families).
The polynesian family has n/a alignment, dependent marking, inflectional plural (albeit via a separate word but still), decimal number system, and prepositions.
None of these features can be characterized as "(indo)european" in the strictest sense.

I wasn't saying that other language will necessarily lack these traits, but that they might lack them.
Nor did I claim these traits to be exclusively indoeuropean.
So I don't quite understand your answer.

nornen:Those features might not be usual or known in other languages.

Bottom line: If you were an alien linguist from Kashyyyk, there is a high probability that you would be able to trace Esperanto back to its european roots (without even considering the lexicon/vocabulary).

If you cite those characteristics as "proof" that Esperanto is a European language, thee may as well have said it.

Only if the Kashyyykian linguist was a very shallow researcher.

Read M. Piron's essays cited in an earlier post.

Nornen is right in that sence, that not the single features, but the combination of the features is clearly (Indo-)European.
However, many of Esperanto's features, like N/A-alignment, SVO, five cardinal vowels, (moderate) right-branching, are typologically very common all over the world and would be the natural choice for an international auxiliary language, even if this should be constructed based on all languages of the planet.

It doesn't really matter how you classify Esperanto. The only thing that matters is whether Esperanto is easier to learn than English for speakers of non-European languages.

In any case, I am not aware that, say, Japanese speakers object to English as a world international language because it is too European.

And there are plenty of features of Esperanto, like spelling matching pronunciation, regularity and systematicity, lack of opaque idioms and fixed expressions, liberality of word-building, and so on, which make Esperanto easier to learn for an adult regardless of linguistic background.

Also, if Esperanto is European in character, let us not forget how much of the developed world outside continental Europe speaks a European language anyway.

I say developed world, because if you live in Africa scratching a living on less than a dollar a day, you are not going to be too concerned with any Europeanness of Esperanto.