Actually I think the Qur'an is relevant, but only because it was written in the 7th century CE, not before. And not in the way you think.
The origin of Islam only existed with Muhammad, also in the 7th century CE. Before Muhammad, the nomadic Arab clans and tribes were polytheistic.
Yours (and other Muslims) assertion that the Qur'an (and Islam) existed before Muhammad's time and that Allah is the original author of the Qur'an, is only based on faith, not facts. You have no physical evidences to prove such thing, just as you have no evidences of the existence of a god.
Qur'an, Islam and Muslims only began with Muhammad, and without supporting evidences they didn't exist until Muhammad. If you believe it to be so, then I can't argue you what you believe because you are entitled to your belief and faith, but don't confuse faith with fact, because they are not always mutually inclusive.
You have no proof of the existence of jinn, let alone angels or demons, and more importantly, of Allah (just as Jews and Christians have no proof).
And I need far more than just your prophet's words (or any other prophets' for that matter).
In fact, Abraham was in Arabia before Mohammed and that's how ALL Arabia without exception entered to Islam. Then later on idols were brought by a leader of one of the tribes, and this is how they set up partners with Allah. They weren't originally pagan, but they worshipped idols along with Allah because they thought it will make them closer to Allah. So, there you go, Islam was there before Mohammed.