It's interesting that you picked Spider-Man as the example of creating a different character being a better alternative, because there are plenty of racists out there that really hate that Miles Morales is even a thing. They would say "Why do we need a black Spider-Man? The original was fine!"
It's almost like racists are only ever going to whine about inclusivity, and "characters remaining their own race" vs "creating new characters" is a moot point because the people out there who are upset by the former are going to be upset by the latter anyway.
Imagine if the new scooby show had a cast of all white kids and a single black, well written character was added and made a pivotal role in the gang. The exact same people complaining now about race swapping would be complaining then about the new character being shoe horned in because of "woke" inclusion. Just like they do with Miles Morales.
The answer is just that we need to keep creating media with both of those scenarios and accept that shows created with a single color cast are products of their time and we can do better now. Racists aren't going to be happy either way.
Edit: Bring on the downvotes. If you consider "they're not supposed to be that race" as a valid, lone criticism of a character, you might have to ask yourself some difficult questions.