Agreed. Plus it is a satire. It was making a point. It wasn’t required to be factually accurate through the entire movie.
My disagreement was that there was any evolutionary downward pressure on human capability. We can do increasingly dumber things without it being a genetic change. Propaganda, indoctrination, and selective access to information can play a huge role in how people develop and ultimately behave.
Natural selection isn’t the only thing at play though. That solely refers to the organism best adapted to the environment being more likely to survive and produce offspring. Essentially everyone in our population survives to be able to produce offspring.
Sexual selection plays a much bigger part now. That isn’t someone being the most adapted to the environment, it’s someone being the most attractive to a mate. There are plenty of adaptations across nature that are maladaptive to survival, but are selected for regardless.
Then there are random mutations and genetic drift. Those happen in every population. That is more just a matter of chance.
We have found ways to adapt to our environment outside of evolution. So we no longer have a significant natural selection process.