with your "best" Thor film, that honor is still held by the first one. The inane, insipid, lame ass comedy destroyed this movie IMO.
I wouldn't say humor in general weakened the movie so much as specifically bathos. This video details what bathos is: https://www.youtube.com/watch?v=w-QhdzQo66o
The video mentions Spider-Man II as an example of a movie that is NOT infected with bathos. Note that this doesn't mean that the movie lacks humor. There is plenty of humor in Spider-Man II. But the humor is never used at moments where it would destroy drama. Humor that pops up in moments that should have a gravitas, and which destroys that gravitas, is bathos, and it's become the main weakness of the Marvel movies. Not enough to ruin them, but enough to make them much less than they should be.