An interesting twist would be a universe with no superpowers at all. The characters and their casts exist, but they simply don't have superpowers. Of course, as countless films and TV series show, you don't need them for a series to be entertaining or even have action.
For example, take the idea of Spider-Man in high school and do something like Riverdale or Dawson Creek. Take Captain America and make something like Die Hard. Take the Fantastic Four and make The Martian. Take a gang of street-level heroes and make Brooklyn 99.