many popular iconic actors were neither in as huge a sci-fi movie franchise as he nor are they of his race. Remove those and he has almost zero nominations, let alone wins. His wiki displays nothing in the way of humanitarian efforts, though I'm sure like most he has been involved in some things. Few of his movies beyond the Avengers franchise are really even highly rated.
I'm not disparaging the man or those jumping on the band wagon. He seemed very personable but his actual impact on the profession or society, as opposed to the impact of a role he played, doesn't jive in my mind with the accolades being heeped. Beyond normal celebrity, he seems hardly noticed.
Even Obama's quote, "To be young (he actually wasn't), gifted, and Black; to use that power to give them heroes to look up to .." Well he actually didn't. He didn't create the roles. He didn't write the roles. He didn't direct the roles and he only co-produced Marshall. He simply acted them. If not him, any of a number of other actors would have capably filled the role. Whoever is looking up isn't to him, but to the people/characters whose roles he played. If he's not in the Avengers series, i think his death is a small line at the bottom of CNN.