I think it comes down to how you define “superpower.” If were just talking mutations, I think superspeed and super-strength would be the most plausible.
Think of someone line Michael Phelps. His physical attributes make him - compared to most others - inhumanly fast and strong due to his wingspan and body structure. I wouldn’t quite call it a superpower, but I think deviations in size and body comp could lead to abilities deemed “super.”