So she taught him languages and scripts nobody knew anymore?
Taking your unlikely speculations as fact and presenting them as such is a bad habit.
You can stay with the thread ~ to wit, that the Koran has something other than divine origins, and that among its sources are texts other than those we find in the Bible, but which are contemporaneous to the Bible, and may derive from other materials which the Bible itself references.
You have argued that Mohammad was illiterate (and that was his reputation, but we do not know it for a fact) and therefore was unable to directly read ancient texts. I merely asserted that Mohammad probably could read (and he most certainly could read after his encounter with the angel), and that he had associates who could read, and that there were other people at Mecca who could read pre-dot Arabic, and most likely a variety of other writing systems and languages.
Mecca was, after all, a major stop on a major trade route in the Middle East. Such places attract knowledgeable and talented people.
Your final argument, to wit: "take your unlikely speculations" to someplace else, pretty clearly identifies you as an Islamist who's not willing to face up to the fact that God didn't deliver the Koran to anybody named Mohammad!