Protons are incredibly complex quantum critters, it turns out! Most learn they are particles stuck in the nucleus. A few learn they are not fundamental particles, but instead made from quarks (2 ups, 1 down). And basically no one learns they are complex, changing bags of gluons and quarks, in a quantum world where just about anything goes! The theory of what happens in the nucleus and nucleons is quantum chromodynamics (QCD), which is a difficult mathematical theory, to say the least.
Check out this article from Quanta Magazine (which I also highly recommend)!