On High and Low IQ

 A higher or lower IQ is not exactly the same as better or worse intelligence.

A higher IQ suggests a greater capacity for accumulating and comprehending information and knowledge—that is, for handling complexity. Even so, it is important to emphasize that IQ tests measure potential rather than actual achievement. Therefore, a lower IQ tends to reflect a simpler form of intelligence, or a reduced capacity for accumulating and comprehending information and knowledge—or for dealing with complexity.

In any case, "simple" is not worse than "complex."

It depends.

Oversimplification and over-complexification are equally bad.

Being "less intelligent" refers more to being "cognitively simple" than to being "foolish"—if we define "stupidity" as an inability to comprehend or possess self-awareness (an ignorance of one's own limits and potential), even though this may correlate with cognitive simplicity. After all, there are many individuals with more complex intelligence who act stupidly—emotionally and/or intellectually—such as by fervently believing in fake news because they are unable to control their own cognitive biases.