1) Alexander the Greats legends, true and false, appear in 80 languages, from Iceland to Malaya. The Parsees curse him for destroying their holy books.
In Central Asia he is Iskander. His red silk banner is still displayed in Ferghana, in Turkestan. Chiefs claim descent from him, their people claim descent from his soldiers, their horses from Bucephalus.
He appears in the Koran as Dulcarnain. In legend he explored as far as the Ganges, the Blue Nile, and Britain. He travelled to the heavens and to the underworld. In legends, he went indeed to the end of the world, and even to the bottom of the sea, where the very fish paid him homage.
He was the son of Apollo, according to his own mother, and there are signs that he believed this. At Gordium, he cut the fabled knot.
He tamed the wild horse Bucephalus with a word and a touch.
2)A Skye legend tells of how the Dunscaith Castle was built in a single night by a witch or faerie "All night the witch sang and the castle grew up from the rock with tower and turrets crowned; All night she sang, when fell the morning dew 'Twas finished round and round".
3) Darwin is rumoured to have become a Christian on his deathbed.
4) People dispute some of Napoleon Bonapartes achievements as legend.
My point is that stories are always invented about great people of history. Is it possible that some if not all of these stories are legend, especially since they did not make it into the Quran itself as you might expect they would?