In discussions about intelligence we're always talking about the ability to acquire knowledge, not knowledge itself. Sure colloquially those might be conflated but having knowledge is not the same as being intelligent. There are brilliant minds that have very little knowledge, that doesn't make them less intelligent: it makes them less educated.

We know that intelligence is genetic at some level. We share 98.8% of our genome with Chimps. Somewhere in that 1.2% lies a vast gulf of intellectual capacity that isn't there for a chimp, regardless of the heights to which a chimp might climb intellectually. In order for them to have greater intelligence than they currently possess as a species they must change.

I'm not saying that there is some way to breed for an ubermensch, I'm saying that 99.9% of all humans have the same DNA and that in that encoding there is a maximum level of brain performance possible for any person.

Humans with intellectual handicaps have a lower maximum level of learning than some. Neurodivergent humans (doing some massive hand-waving and generalization here as a member of that community) have some higher possible maximums in some forms of intelligence and lower in others, and we're pretty damn sure Autism has strong genetic components.

What's absurd about the concept of IQ tests is the attempt to boil down a complex and multifaceted topic into a single number that they can tell in a 200 question multiple choice quiz, not that Intelligence (in all its various hues) has nothing to do with genetics.

All of which is to say that Learning is the application of intelligence.

As for saying Intelligence is 100% determined by genetics? I expect there's a lot of external factors that come into it: We know a lot of genetic expression changes through quick reacting epigenetic factors. We also know that brain development can be stunted by nutritional issues.

But we also know that ancient humans had incredibly rich and diverse lives and the more you research about them the more you see the echoes of our same sharp minds reaching out across the gulf of the centuries. They weren't less intelligent than us. Anthropologists classify "fully modern humans" as 30000 years ago.