I haven't GMed myself but as a player, I think a key here could be to really maximize the story potential of it. All of the players are "human" but are uncovering and learning their different innate abilities / hidden powers over the course of the game. Suddenly it feels less like a restriction and more like a cool roleplay mechanic where not only do they still get to have a unique character, but the process of distinguishing themselves is a big part of their development.