Hate to say it. But the Marvel movies are not as good as people keep making them out to be. Iron Man, Captain America, Doctor Strange, Thor even. They look nice but totally screw up the characters at every turn. Some of the sequels arent bad. Winter Soldier I liked and Avengers. The original X-men and Spider Man movies werent bad really. But the movies after progressively deviate from the source to the point they are approaching "in name only". Endgame in particular treats the characters so horribly.
One of the problems you have with the Marvel characters is choosing which version of the characters to adapt. Some of them have changed radically over the years. For instance there are long stretches of the comics where Thor isn't Thor, and Tony Stark isn't Iron Man. The Marvel team did an excellent job of choosing which elements to bring together to make the movie versions of the characters, and which to leave out.
Even then, though, there were a lot of classic storylines that they simply didn't get to tell. They never really did Demon in a Glass Bottle for Iron Man, or Armor Wars, though they hinted at both in Iron Man 2. They never really did a classic standalone Captain America storyline where he simply fights some bad guys, either.
I also don't particularly like what they've done with Spider-Man, though Tom Holland is very good in the role.