What's the point of IP if the conjecture is that creativity is solved? Why not just generate different IP?

Because the value of IP is stored in cultural zeitgeist. People don't want to go to "A mouses fantasy location" they want to go to Disneyland.

Convincing people to give a shit about your IP is a totally different issue to producing it, in my opinion. There are already countless talented artists a big producer could hire to make them new IPs but it is still incredibly rare for a new IP to take off.

Art keeps getting cheaper and easier to make yet as a society we are addicted to remakes and expanded universes, new seasons of shows that ended a decade ago etc.

Creativity absolutely has not been solved. Theft, however, has been solved.