OK, so the Marvelverse proper is huge and sprawling and does not have one single unifying thread or even ultimate hero. The MCU and its televisual offspring fumbled for a variety of reasons.

One is that while they did have Iron Man, Thor, Hulk, Captain America, Spider-Man and the Avengers, they didn't (or couldn't) make enough or proper use of the other heavy hitters of the Marvelverse - Dr Strange, Fantastic Four, and the X-Men. They should have made sure of ownership of all of these before even starting. Further, they should have kept them apart as far as possible, as they are in the comics.

Avengers should have been built around Captain America, not Iron Man. Hulk should have left the team almost immediately and Thor should be the deus ex machina, cavalry-over-the-hill member. Avengers line-up should be light-middleweights such as Cap, Iron Man, Ant-Man/Giant-Man/Goliath and Wasp, Hawkeye and either Black Widow or Mockingbird, Vision, Quicksilver, Scarlet Witch, Black Panther and/or Wonder Man.

Avengers, Iron Man, Thor, Spider-Man, Dr Strange, Fantastic Four and X-Men (Cyclops, Storm, Phoenix, Colossus, Nightcrawler, Wolverine and Gambit line-up) are the film franchises.

Captain America, Black Panther, Moon Knight (done properly) and Heroes for Hire are the TV series (not too many FX needed).

There would be room also for a shorter film trilogy featuring the orginal Guardians of the Galaxy (Vance Astro. Martinex, Charlie-27, Yondu, Starhawk/Aleta and Nikki) and their war against the Badoon. A TV mini-series or movie of the original X-Men (Cyclops, Marvel Girl, Angel, Iceman, Beast, Havok and Polaris) would also go well. Perhaps Alpha Flight in some form.

Wishful thinking, but with so much material to go at, how come after a relatively short time they were reduced to rummaging in corners for minor characters to make into films and shows!