One of the best writing analogies I've heard is: A novel (or campaign for RPG purposes) is like a game of chess with the pieces being characters. If you ask the king what the story is, he'll say "It's a story about a clash of mighty kings." If you ask one of the pawns what the story is, he'll reply "It's a story of a pawn who was sent into battle."
Assuming the power pieces are the heroes, your PCs would be the pawns. They are still the protagonist of their story, and there's no reason that story can't be more compelling than the stories of any of the other pieces.
Assuming the power pieces are the heroes, your PCs would be the pawns. They are still the protagonist of their story, and there's no reason that story can't be more compelling than the stories of any of the other pieces.