Again, what do the solo movies have to do with this? You don't need to see the solo movies to understand and appreciate the team aspect of Avengers. If that was the case, then it wouldn't have made more than the highest grossing Marvel film, IM2, in 14 days would it? It isn't just people who saw the solo films watching Avengers, the numbers indicate this. You're so incorrect it's not even funny.
Avengers is strictly a stand alone film that perfects the team aspect that the X films failed to execute. The numbers don't lie.