Well in the "the real treasure is the friends we made along the way" I'd say the real villain of the show is fear. Catra is afraid of loss, Shadow Weaver is scared of rejection, Hordak is scared of failure. Almost all of the bad guys in the show are redeemed when they realize they can be courageous and stand together with friends instead of lashing out
Lol JK, Shadow Weaver is a bitch