Not a lot of diversity , check out the pics at the top of this page, it's whiter than a Klan rally during a snow storm
First of all, the Avengers was created in the 1960s, before diversity was an issue, so you won't see a lot of it if they make movies based on the first 30 years of the comic. I've watched the Wizard of Oz more times than I can count, and I never see any diversity among the Munchkins. Should the studios be penalized for that retroactively?
Second, how many white people is too many? Because if we're to aim for genuine diversity, should the Avengers only have as many white people as make up the population of the United States? Or the human population in general? And do we try to include all minorities, or are a handful of blacks enough to qualify as diverse(because in America, diversity is often translated into opportunities for blacks, Latinos and certainly Asians are quite invisible)?
And if your question, which implies systemic white racism(why else mention the Klan), is to apply to companies like Marvel and Disney, then what about other entertainment industries? Should Hollywood be required to reduce the number of Jews in its employ to more accurately represent their numbers in the broader population? Should professional Basketball be required to demonstrate greater diversity? Or does that concept only apply to white people?