Is the wisdom behind the Prophet being illiterate to prove that the Qur’an is not from him, such that it necessitates that an educated person could produce something similar to it?

The Prophet being illiterate is a sign of his truthfulness and proof that the Quran is a revelation from Allah. This does not mean that a literate person could produce something similar to the Quran. Rather, it emphasizes that the inability of educated people to produce anything like it is proof that it is not of human making.

The Quran records this fact to make it a proof of its truthfulness, as in the Almighty's saying: {And you did not recite before it any book, nor did you inscribe one with your right hand. Otherwise, the falsifiers would have had doubt.}

The claim of the disbelievers of Quraish that the Prophet wrote down the Quran is false, because they knew of his illiteracy before the prophethood. If he had been able to read and write, that would have been a cause for doubt.