I think the point is that Feynman came later to contribute to Quantum Electrodynamics, the "first theory where full agreement between quantum mechanics and special relativity is achieved."*

* https://en.wikipedia.org/wiki/Quantum_electrodynamics

Feyman was too young for the really fundamental work on quantum mechanics. He won his Nobel prize for his work on quantum electrodynamics. However, he created the path-integral formulation of quantum mechanics, which can be thought of as another way of describing quantum mechanics.

Yes, echoing the others Feynman was too late for the foundational, completely change your view of the universe stuff.

Gamow's Thirty Years that Shook Physics: The Story of Quantum Theory http://www.amazon.com/Thirty-Years-that-Shook-Physics/dp/048... is the standard non-specialist account of this, it starts with Plank right after the turn of the century and is essentially complete in 3 decades, about when Feynman was in high school and teaching himself serious math.