I recall noticing, when I was 16 or 17, that the mass of a neutron was about the same as that of a proton plus an electron, and then writing a "paper" proposing a theory that a neutron was no more than proton with an electron, so that electrical charges canceled out, the masses added up, and electromagnetic forces bound them together. in a nucleus, electrons would "orbit" the protons in such a way as to bind them together, since the distance between a proton and its neighbor proton would be at least twice as much as their distances to the electron, so the repulsion would be much smaller than the attraction. I didn't have the maths to express that as quantum mechanics, wave functions and whatnot, but it looked like a beautiful simplifying theory to me back then