Why Einstein is important to so many? didn't he contribute to the creation of the atomic bomb? Some of the greatest humans are the ones never mentioned.
I vote for Plato , not only for the great things as pioneer made but also that he chosen to be in the shadow of Socrates legend that he gave light in order just to pass those messages.
This was exactly what the OP asked not to mention. oh lol... For me, the greatest human in History is my Mum.