IQ doesn’t measure overarching intelligence, it measures how well the underlying subsystems can perform certain low level tasks. Having good neurological machinery (in the readily testable functional areas) does not mean the state of the overall system is such that they’re coordinated, communicate, and ultimately used properly.
You can have a very, very, poor system made of incredibly good parts. And that system may never encounter or be composed of the means to pattern itself in useful ways.
IQ measures a person’s ability to learn, not necessarily their application of it, the amount of knowledge they have, the veracity of that knowledge, or their ability to think critically in terms of decision-making and questioning their preconceptions.
That’s to say, a thirty-year-old with an IQ of 100 has a lot more knowledge than and will make better choices than a ten-year-old with an IQ of 160. Alternatively, the 160-IQ individual may have dedicated that learning propensity to something useless like dated technology, conspiracy theories, or maybe nothing at all.
IQ is a single measurement of intelligence, a multi-faceted and complex concept. There are IQ tests that break intelligence down into multiple sub IQs, those tests are fairly informative, though still insignificant when discussing intelligence. In the same way, IQ does not make you virtuous, or confident, or energetic, or clever. It simply allows you to recognize patterns faster than someone with a lower score.