It is true that we should not reject or accept an idea without enough studying of it, but the claim within the subject of the post seems unacceptable a bit.
The first point:
As far as I know, Arabic, Hebrew, Aramaic and all the other Semitic languages have a common root.
"Arabic" does not have any meaning before Prophet Abraham because Arabic means the language of Arabs, and "Arab" did not exist before Prophet Ishmael/Ismail, the ancestor of Arabs! (Dear Dr. Shabbir has beautifully written the brief history of Jews and Arabs in QXP, the author's note of Surah 14)
Did human not have any language/tongue before Prophet Ishmael?!
There are many foreign words in the Quran such as Injeel (Evangel, a Greek word from the root of euangelion), Istabraq (Estabrak, an Old Persian word means silk), Iblees (Diabolus, Greek), Zanjabil (from a Persian/Indo-Aryan root) etc.
Are these words not loanwords?
Without any doubt, Arabic has many good features (e.g. Ishtiqaq, accuracy and rich vocabulary) that candidate it as one of the best mediums for conveying the revelation. However, we should not exaggerate!
Arabic is not Language of God, it is only a good language that He used it as a medium because the audience of His final revelation were Arab. The Quran could be sent in another land like Greek and in the language of that land.
Arabic, the first language or the mother of all languages?!