So half the population is not normal then? Seems a little extreme. I have no idea what being Feynman is like, I'm sure he has no idea what being a "normal" person is like. Many people claim to be ordinary, but some are simply above or below (with respect to any arbitrary metric).
I think that dozens, if not hundreds or more "ordinary" people have tried to do what Feynman did, by studying hard. They did not succeed.
When I see claims like that I immediately think the claimant is engaging in humility and self deprecation. Nobody likes an arrogant ***. Better to lay on the politically correct platitudes.
I think Feynman reported he scored 125 on an IQ test he took. That would put him about 2 standard deviations above 100, which in some regards is surprising. You would think that someone we consider to be a super genius would score much higher. 125 is what I would normally expect to see from a PhD, and assuming that the 125 is his score, then perhaps the lesson to take away from Feynman is that while yes it is important to have the aptitude, it's perhaps of greater importance to have the ability to properly use that aptitude.