You left out Hulk, which i would argue was A tier since he had a very popular tv show in the 80s and a big budget film in the early 00sOf course, Guardians of the Galaxy is D-Tier...but they made it work.
Spiderman is A-list
Ironman/Thor/Captain America are B-Tier (pre-MCU)
Ant-Man/Black Panther or a Captain Marvel is C-Tier
Guardians/Shang-Chi/Eternals and the like is D-Tier
They made Guardians hit, so if thr stories were there there it still should've hit.