Yeah, I think that what a lot of people miss in this conversation is that there really is this thing that strongly correlates better performance on IQ tests with better performance in all sorts of other otherwise-unrelated things.

And at the same time, training for better performance on IQ test questions does NOT increase performance on those otherwise-unrelated things.

So it's that thing that correlates across those unrelated things. That's what the intelligence researchers define as intelligence, even though it's popular to redefine it as something else that is entirely nurture and not nature.