There is one point to remember:-
There is nothing new under heaven
Sauron could be any bad historical figure Hitler, Franco, Ghengis Khan, Attila the Hun and a hundred others the story is an old one retold a new with different parts of old tales it is a basic tale of good vs evil told in a new way a lot of his life proberly influenced the story either knownly or unknownly but at the end of the day it still is a great story well written and will be remembered for years and years to come