Earlier quoted context omitted.
In a debate about how things work, "you're wrong because we know you're wrong" isn't a useful argument. As to comparison to other animals, we also know that there is a genetic component to being able to live under water, as fish can do this and humans can't, this doesn't mean some humans are better than others at living without air.
The difference being that humans aren't descended from fish, but are descended from apes. We know that some kind of incremental genetic "improvement" to our intelligence must have evolved and then become universal throughout the populations that speciated to become modern humans.
Second, is there any evidence that the evolutionary history of intelligence was linear? How do we know that there wasn't a binary-like change where one generation didn't have our level of intelligence and the next did, and all humans today are descended from that single change, as opposed to it happening gradually?