Not a fan of changing IM Thor Cap Hulk Spider and all the old school characters to different people.
The diversity thing is extra irritating. Just push some black Asian female characters. Make these new jacks sidekicks or something.
As a comic fan.
Everyone you named (except Hulk) is not an inherent character, its a costume & title.
There were at least 5 Captain Americas, 5 Spidermen, and like 20 Thors before the current black versions.
In the case of Captain America, this isn't even the first black Captain America. Isaih Bradley is. And Rhodey has used IronMan's armor before on many an occasion. (It has its own protocol set just in case he winds up in it)... So Marvel is just doing a better marketing job advertising its diversity now so it seems more in your face, but they've been doing legacy characters since the 40s. Legacy characters go back so far that most don't realize that the 1st Human Torch isn't even a member of the fantastic four. He predates the fantastic four's debut issue by 20 years. There has been more than one Ghost Rider, etc. The list goes on.
Legacy is just a part of comics.
I think adding a new identity to the legacy is fine.. as with Ben Riley or Miguel (the black/puertoriquan spidey) cause Peter Parker still exists unaltered.
On the other hand, when they change a base character like making white Nick Fury into Samuel Jackson... thats where it gets weird.