@Reynard -- The old Savage Worlds GM in me is trying to think of a way to balance what you want. Savage Worlds really does ground itself around "action hero++" style gaming, but I've never pushed it up a notch to superheroes. To make a SW game that allows "muggles" to go after the superheroes, it feels like you've got to create some built in backstory/narrative conceit that even gives the non-supes a chance at all.
If the supers are really that much better than the muggles, I don't know how you balance the numbers between damage + toughness across the spectrum of character effectiveness. Otherwise, the whole premise becomes "the PCs go find the MacGuffin that lets them actually hurt/wound/kill the supes."
Or you're doing what Savage RIFTS did where it uses a different damage scale entirely, and weapons have to work within the right damage scale to even have a chance to hurt the supers, etc.
For Savage Worlds, it just feels like a bunch of narrative conceits have to be baked into the premise to even make it work.
And if you're going to be throwing around a bunch of narrative conceits, might as well do it with a narrative-style system.
Like I could easily see hacking Starforged for this purpose, just by creating a few new player assets but otherwise running it as-is.
*Edit: Thinking about it, taking 2-3 hours to brainstorm assets, I could easily see a hack of Starforged being a really, really fun way to run that game. And I can easily see why others would recommend PbtA or FitD style games as well.