Is every ring a homomorphic image of some abelian group's endomorphism ring?
I ask because I've never liked to identify rings as being subrings of endomorphism rings. A subring is basically a ring within another ring, so if you answer "what is natural about the ring axioms (and by extension, rings as a whole)" with "because they are (essentially) subrings of an endomorphism ring", then to me it feels like saying "rings are naturals because they are rings"... well yes, but why those axioms?
I'm a beginner in ring theory. I don't know if this is true and google didn't really help me out here.