Yes, but as I pointed out, also in a respect the Arabic of the Qur'an was not native to the people, it was almost instructional to them. It was one of the aspects of the Qur'an which even the Arabs themselves could not explain and were amazed by. In so many places the Qur'an uses the phrase: "What is <such-and-such>? And what will convey to you what <such-and-such> is? It is <explanation>". It sounds a lot better in Arabic, but the Qur'an came to redefine the language in a sense, even it's vocabulary.
I would not say that the Quran redefined Arabic any more than the King James version of the Bible redefined English. English speakers are influenced by the language of the Bible because so many have studied it for so long. Again, that kind of influence is to be expected.
Pretty much every single aspect of the language.
If you cannot name any specifics, then it seems likely that you have nothing specific with which to back up your claim.
It's precise place in the Arabic language sphere of the time is still unknown and debated. Some believe it was just the polished dialect of Makkah, others believe it was a common literary dialect used for poetry competitions, yet others that it was a form of the language specifically developed for the Qur'an itself. There is very little evidence of it having existed much before the time of the Qur'an, with few, if any (specific) attestations until the Islamic period.
I don't know where you are getting your information from, but it isn't from linguists, who have expert knowledge of all known Semitic languages and objective methods for answering such questions. There is absolutely no reason to believe that the language of the Quran was special or different from other languages.
True enough. I don't think to quite the same extent though. Also since Latin has no closely related sister languages, it's very difficult to make the same comparisons. Same goes for Sanskrit too I think...
Not true. Latin had plenty of related "sister" languages and a popular vernacular. The same was true of Sanskrit, about which we know more than any other ancient language, thanks to its superb tradition of linguistic scholarship. The spoken languages of the time were studied by scholars, who called them "Prakrits".
When we compare Arabic (fusha) to all it's sister languages though, we find it's a very different story. Whilst Arabic dialects are almost on the same level as the sister languages. I don't think the same situation occurs with those two.
I have never heard any such claim by a reputable language scholar, and you have given us no details or sources for your claims.
It would almost be like if proto-IE had been mostly preserved in a certain IE language...
You obviously don't know about Hittite. When Proto-IE was initially reconstructed in the 19th century, Hittite records had not been deciphered. When they were in the 20th century, it was discovered that the Anatolian peninsula was full of Indo-European languages, and they contained a lot of information to confirm and inform the reconstruction of Proto-IE. Anatolian (of which Hittite was the best known exemplar) has often been considered a "sister" branch that broke off of the main IE trunk earlier than the other daughter languages.
Arabic contains a large degree of the features that linguists suppose existed in proto-Semitic. If one reads a comparative grammar of the Semitic languages, one will find fusha Arabic being used continuously as the reference source for all the other languages.
Again, you give no specifics, but this is not surprising. For example, Lithuanian is often cited as a modern IE language that retains a number of features that resemble earlier versions of IE languages. Some languages are more conservative than others. Proto-languages are constructed from a comparison of the earliest written records of sister languages (if such records exist), and proto-Arabic would likely contain many features of proto-Semitic.
I used the term letters, since most would not understand linguistics terminology too well. I correctly meant phonemes. Hebrew has lost about 7 or 8 of the original proto-Semitic phonemes, as have pretty much all of the Semitic languages, except Arabic.
You can just use the word "basic speech sounds" if you want a non-technical term for phonemes. And phonology is a lot more complicated than just phoneme inventories. But comparing early versions of Hebrew and Arabic in such general terms does not support the claim you have been making about Arabic. There was nothing linguistically unusual about al-Fusha.
I would agree if it were randomly spread out like that. But in the Semitic language group, pretty much all of them have merged phonemes and simplified grammar to a similar degree, except Fusha.
I think that you need to become more knowledgeable about the mechanisms that govern linguistic change before you try to draw conclusions about al-Fusha in comparison to other literary and liturgical standards that have arisen in other cultures.
If all Arabic dialects had been similar to fusha prior to the Qur'an that theory might be valid, but they were not.
Not at all. Literary standards are seldom drawn from "all dialects" of a language. They tend to reflect the dialect of the most powerful tribe or national group within a culture. Just as American English has standardized on the Midwestern version of the Northern dialect (as opposed to other competing dialects), Al-Fusha would have sprung from a single dialect source.