Asalaamu alaykum, brother,
Thank you for bringing up this important topic.
First of all, I have to say: your question is wildly biased and bigoted. We cannot ever assume that being Arab gives us some sort of distinction in the eyes of God.
Prophet Muhammad made this point very clear:
There is no superiority for an Arab over a non-Arab, nor for a non-Arab over an Arab. Neither is the white superior over the black, nor is the black superior over the white — except by piety.
Now to the core of the question: did Allah intend that all humanity should come to Islam?
Of course. Of course, He did. He is Rabb al-3alameen, the Lord of All the Worlds, not The Lord of the Arab People.
As for why He says He revealed the Quran in Arabic, many wiser people than myself have debated on this topic for centuries, literally.
For one thing, God actually sent many prophets before Prophet Muhammad, and not all of them were Arab or spoke Arabic.
We have not sent any Messenger except with the language of his people so he can make things clear to them. Allah misguides anyone He wills and guides anyone He wills. He is the Almighty, the All-Wise. (Qur’an 14:4)
Jesus most certainly did not speak Arabic; Jesus spoke Aramaic. And a little Greek, probably.
Moses didn’t speak Arabic because he lived in Egypt, among his own people: Hebrews. So Moses spoke Hebrew.
Noah….we have no idea what language he spoke! Or Abraham. Or Job. Or any of the prophets that God didn’t mention in the Quran.
So, it’s very clear that God sent Prophets to all people of the earth at one point or other, and they all spoke the language of the people they were being sent to, not Arabic.
But Prophet Muhammad, who received the revelation of the Quran was an Arab, and he did speak Arabic, so God revealed the Quran to him in his own language so that he could deliver it to his own people.
We have made the Qur’an easy in your language so that they may take heed it. (Qur’an 44:58)
He also says,
If We had made it a foreign Quran, they would have said, ‘If only its verses were clear! What? Foreign speech to an Arab?’ Say, ‘It is guidance and healing for those who have faith, but the ears of the disbelievers are heavy, they are blind to it, it is as if they are being called from a distant place.’ (Qur’an 41:44)
Think if Allah had revealed the Quran in, say, Spanish? Would it have benefited the people of Mecca? Would it have challenged them? No.
Some of the greatest companions were non-Arabs, including Bilal, a black former slave from Africa. Surely if Islam was only intended for Arabs, he would not have embraced it or Prophet Muhammad would have told him clearly, “Sorry, this religion is not meant for your kind.”
Allah created all people and wants all people to be near to Him, for our own sakes.