Sorry, not true about the IQ tests. IQ tests measure a particular type of intellience - ability to extrapolate accurate conclusion in terms of logic and reasoning.
This is immediately noticeable when talking to someone. For instance, people wouldn't believe fake news so frequently if they had that ability.
You are right that people who haven't been given the skills through relevant education will not be measured accurately. I see that in my own case. At 10 or 11 years old, I was measured at 165. In early adulthood when I didn't have the math skills required, I dropped somewhat - still genius, but not as high. Then in my mid-40s, I did a test that gave me 5 hours but I could have more. It was only pictures and words. I did it in 90 minutes and scored off-the-graph.
I completely disagree with you that all you measure is people's ability to do IQ tests. What you measure is people's abilityt o arrive at the right answers, and that reflects elsewhere. For instance, in college level math papers, I could get 100% by doing the paper in half the time. And as IQ measures languages as well, I was already published by the time I was 10 or 11 years old. There is a correlation.
I think there is an issue though. People who have greater intelligence are not superior people. Thee life force (for lack of a better word) is the same for all of us. We treat all people with dignity, not because of their talents, etc. - simply because they are live. Life (and the time we spend living it) is the most precious commodity in the universe.