That... actually makes a lot of sense? And is what we should want?

Copyrighting The Monkey King in the 16th century (just roll with it, this is going somewhere) made sense. Over time, that copyright would expire.

Fast forward to the 1980s where Akira Toriyama and Shonen Jump basically retold the story but with a lot more robots, werewolves, kaiju fights, and noseless bald cops. Goku is based on The Monkey King but is not The Monkey King and has gone on a much stupider trajectory to become an alien who is too dumb to live and regularly threatens all of existence with his idiocy. And has canonically fucked two babies into his wife without ever kissing her. That is a new character.

As for "change the color of the nose": (Disclaimer: I am an anime bitch so I am sure this color was already used for Goku as opposed to just Broly but whatever). If you make Goku's hair Green because he went Super Saiyan Fury Happy Dance Now With The Divine Gods, that is not a new character and the rights-holders for Dragon Ball would rightfully send you a C&D. Whereas, if you make an identical clone of Goku but is evil then you have Turles (or Black Goku (or, honestly, Bardok)) and it can be argued as a new character. Whether a third party could get away with that starts to get incredibly messy and dangerous.

The reality is, though, that everything is an evolution of something else. "House, MD" is an evolution of Sherlock Holmes. Superman is an evolution of Hercules. If you couldn't copyright evolutions, you wouldn't be able to copyright anything at all.

In fact, creative commons licenses (like you shared) already address evolutions in the form of derivative works, which you can reserve in CC with the "ND" license type.

It's tricky. Sometimes changing things truly is a creative act. A big portion of Disney's portfolio is from retelling European fairy tales: Sleeping Beauty, The Little Mermaid, Little Red Riding Hood, Hansel and Gretel, etc. It would be hard to argue that they added nothing of value when they remade those fairy tales. In many cases, people wouldn't recognize the original stories because Disney changed so much.

OTOH, it seems like bullshit when tiny elements are changed. For example, the Conan-Doyle estate has sued because although Sherlock Holmes was in the public domain, they said that was only the stories where he was aloof and analytic. They said that in stories published in the 1920s he was more capable of empathy, so any depiction of Holmes where he was empathetic infringed on their copyright.

If I were on a jury deciding this sort of thing, I'd require that there be something brand new. For example, Beauty and The Beast is public domain, and as long as someone is making an animated movie based on that story the default assumption should be that they're inventing new aspects based on the public domain story, not based on the Disney movie. OTOH if they have an animated candle / candelabra, it's reasonable to assume that infringes on the new character created by Disney.