Looking at cast list for main mcu movie characters i don't think it was mostly white guys(it was mostly white if you add white women however),even more so if add the mcu non canon shows that were more diverse then mcu movies.
Now most of mcu movies up to phase 3 main main stars are white men.
For the mcu non canon shows the main main stars up to phase 3 were more diverse.
This is from a few years ago.
The Marvel Cinematic Universe is 61% White, But Does That Matter
https://www.forbes.com/sites/anharka.../#3e2a64c64482
Note- keep in mind a large number of the 61% are white females as well.