Zero dept might have been the wrong term to use but none the less I found the film lacking. I will give an example, at first I was enthralled at the concept of the conflict between Thor and Loki. These are two guys who grew up together and at one point loved each other as brothers. Then Thor shows up in Avengers and comes and takes Loki from the helicarrier and they are on the mountain. You have a moving scene where he still shows affection for his brother and pleads with him to come home and that scene is touching but then after that the film just leaves that all behind with humor action and humor. We could have been presented with great scenes of the two Brother verbally and emotionally unloading on one another. Give us great insight as to Lokis motivation and drive(It was slightly touched on in Thor). There are so many missed opportunities in the movie because they chose the humor route as opposed to creating emotional conflict and drama.
You just gave a good example of depth within the film, but yet again, you're falling back on humor and the lighter tone as a pretense for why it was lacking. Did you expect the filmmakers to dwell on Thor and Loki the entire time, particularly when there were several other members of the team that needed attention as well? That scene gave us all we needed as an audience from the perspective of the two brothers, and even then, to say it wasn't expanded upon was not true at all, because it was revisited when they met again on Stark Tower during the final battle. A truly forgettable alternative would have been to have them simply pound one anothers faces in whenever they met, but each time that they did meet, personal conflict was most definitely present. In fact, even in spite of the humor that was present, Thor & Loki's interactions were among the most serious and sympathetic of any other two characters in the film.
Every interaction between two characters gave us crystal clear insight into what made them tick. The precaution in BW was readily evident when she approached Banner, as was the apprehension and distrust from him. Starks admiration of Banner was apparent from when they first met to their dialogue in the lab, as was Banners fearfulness of his own condition. Steve had a rather overt disdain for Tony's general disposition from the very outset, and this aspect continued to escalate throughout the film. Really, the only character who IMO didn't get their just due was Hawkeye, for obvious reasons. Again, I think you're trivializing the depth that was very much a part of the film.
In all of these scenarios humor never took center stage over character depth, but people like to act as though the film was a festival of wise-cracks and punchlines, which couldn't be further from the truth. Now
I'm certainly not saying that you have to like it, that's just nonsense, but to say that it was dismissed or took a backseat to the humor is a bit crass. One of the best things about the film was the care that was taken with regard to the characters. Avengers did it better than X-Men, IMO.
Seriously, watch Expendables and Avengers back to back and try to say that they're both the same movie. Expendables can get away with it for its self-referential nature wrt to the theme and cast, but when you peel that back, there isn't much else there. Avengers did not do the same, by any stretch of the imagination. I don't believe that the Marvel films are exemplary masterpieces of film making, within the genre or otherwise(Hell, I only like 3 of them myself), but I do think that they have all taken great care to establish and develop their title characters, if nothing else. I simply feel that the general consensus has approached this genre with bias first and objectivity last, in that lighter films = empty camp and darker films = rich depth, and I vehemently disagree. I challenge anyone to tell me that CA:TFA has less depth than Dredd. We're veering off topic here so I'm willing to continue this discussion via PM if you'd like, otherwise I'm fine with agreeing to disagree. Different strokes for different folks, I suppose.