I doubt that without the Khan plot he would have been. Either he would have been naturally skilled, or some sort of human-alien hybrid.
How the fuck do you know?
And I'm sure if, Chang, Soran, Ru'afo, Shinzon, and Nero can--in some way--remind people for Khan, I'm sure someone would have come up with something for Harrison.
Pfft. In what way does a highly intelligent, genetically engineered man from hundreds of years in the past, and bent on conquest and/or revenge remind you of Khan?
Also, none of those things count as an answer, because they would turn my point against me, so you can't think them either.