Dang, this could be an idea for an actual movie.
Yeah, all the heroes aren't original, but I have never seen the villians before. Besides, think of all the people that use all those super heroes now: they aren't the ones who originally made up the characters, they just have the rights to them.
If you actually wish to make it original, kill off all the old super heroes and make some new ones. I'll still enjoy this series regardless of whether you do or not. When I saw the first episode of this I was a little disappointed, but this is a huge improvement. I also like that you added just the right amount of humor. I get sick of people trying to crank out jokes and one liners that I've already heard a million times. I found ever part funny because I wasn't expecting a joke at the moment it was presented. And that's the way it should be, viewers shouldn't see a joke coming into play. Keep up the good work.