Earlier quoted context omitted.
This. Not limited to cats either. I've noticed the same in dogs and even some cows. Same rules apply to humans as well. Interaction early on develops personality and intelligence varies genetically by a wide margin.
Intelligence is not well-defined even for humans, and we have little understanding of what goes on in an animal's "mind", yet people like you use terms like IQ for cats like they're established facts. For all we know, it could be that some animals/cats just don't "care" as much about interacting with humans. Just like some humans do.
Personally, it's pretty easy over time to tell the difference between apathy and intelligence when you spend a lot of time observing interactions.
"People like you" should check your tone btw.