All I can say is this, for those of the Christianic faith, the book of Jude references in it the book of Enoch, and if you read that it gets pretty wild from there.
Yet it also makes alot of things make sense, including many things that would seem impossible.
So could it be true about Alexander? There is much information and evidence of lines of humanity superior and extraordinary than the average, existing and doing great things up to this day, so I don't rule it out.