Goody goody gumdrops for you.
Where does a Paladin's power come from? You will DEMAND it must be a god, the paladin must be empowered by a divine being. Nothing else makes sense to you, because otherwise, how can they do things humans cannot do?
Me? A paladin's power comes from the unshakeable convictions they have to their oath. That oath can be to a god, sure, but a paladin is someone who has bound their own soul with strictures that the universe itself cannot bend. And when you are in a fantasy world, and you have convictions that the gods themselves cannot bend, only accept or shatter, then that MEANS something. It grants you abilities beyond the petty limitations of flesh. How does that work? I don't know, how does love's first kiss break a curse, or a broken heart turn you into foam.
You can say "magic" but for DnD, Magic is spells. And I am fine making that distinction between spells and supernatural abilities fueled by the romantic ideals of the self moving the world. Of FANTASY.