I feel like this would be fun to discuss. No need for any real seriousness. I want to brainstorm ways for "natural" characters to be competitive with other superheroes.
The easiest is the "superman" way, where your character has super powers due to every member of their alien race having them, but if we include that we are making things too easy for ourselves.
Some other possibilities are psychic powers and/or mastery of Chi, but those come close to the edge of mutation and magic, since a psychic has to start with some psychic potential, and Chi could be considered a kind of magic.
I think the most fun is imagining some body builder and/or athlete becoming so athletically skilled that they are competitive with real super heroes. I guess that is Back Alley Brawler's origin?
Another option is the "Indiana Jones" type approach, where the character's powers are really the result of wit, some skills, and huge amounts of "plot armor".
Batman kind of straddles the line between "natural" and "tech".