I said "most people" and "most things" because yeah, some people really do have a low level of general intelligence and will struggle. I know a social worker whose job for a very long time was finding employment for people with IQs in the 50s, and they really struggled with a lot of things. There is a lot of research into IQ demonstrating that some kind of underlying general intelligence probably does exist.

The point of my post was not to deny this, but to assert that what we perceive as intelligence in our day-to-day lives might not be something as deep as that.