text: I'm sure he will have his fair share of screen time in the actual film. Why would they let the most unknown one have a big part in the trailer? Not as good for marketing as using Iron Man, Thor & Captain for the big trailers. Renner will shine in the film though I guarantee. He is a great actor & award winner like you said.
  That actually makes sense. Iron Man is really the selling point of this movie. I read on box officemojo.com that Disney combatted the unfamiliarity of the other characters by selling the movie as "Iron Man and Friends", which sounds cheesy at first glance but in a way this is Iron Man 3 with a few extra buddies thrown in and that's not a bad thing.
  Actually, it is a VERY bad thing. Iron Man had two movies already: one of them was decent and the other one sucked. Let the other heroes shine too, not everyone cares (or even likes, for that matter) Robert Downey Jr/Tony Stark. Marvel needs to quit shoving Iron Man in our faces! By the way, Captain America *IS* the leader of the Avengers, after all.
  Understand though, Captain America is going to start this movie as a reluctant hero, and his leadership probably won't start to emerge until at least the end of the movie.