Superman is who he has been portrayed for the last 70 plus years. Changing those cores doesn't make him Superman anymore.
Superman has changed quite a bit since his inception. Which is natural, considering the amount of change we've had in the world since he was introduced.
I have two requirements from an actor playing the character, that he be able to act and that they have the physique needed for the character. Whether he is Clark Kent or Calvin Ellis, I have no problem with opening up the race that plays the character.
For me, I'm pretty attached to the original Star Trek gang, I've been watching for forty-plus years now. I have no issue with them changing the race of Kirk and/or Spock. I just want good actors playing the parts.