Of course the comic books are mostly for Americans. How are you going to sell a book anywhere else that features truth, justice and the American way?
All these other ersatz superheroes are nothing more than attempts to ape Batman, Superman, etc,,, Point me to a foreign superhero that existed in the 1940s. “Me too’s” for the ‘60s are clearly guilt inspired ,,,”oh yeah,, we probably need a superhero too” things.
There weren’t that many superheroes in the 40s. And not all comics come from America, most of Europe has a comic tradition, but we don’t read those over here. Of course if you’re going to talk roots you need to remember that Batman is really just a ripoff of Zorro.