Q: Do Superman-esque characters like The Sentry or Blue Marvel work in the Marvel Universe? -- @SuperSeth64
A: You know, Seth, this is one of those questions that seems really simple when you first look at it. I mean, it's a yes or no question, so the short answer is about as short as it can possibly be. The thing is, the reasoning behind that answer has to do with how entire shared fictional universes work and how they've been influencing each other for the past 50 to 70 years, and how one character in particular has defined an entire genre that came to dominate the medium, so for the long answer, well, I hope you've got a few minutes.
If you don't, here's the short answer: No. No they do not.