Intelligence is an abstract and broad concept that doesn't have a clear definition agreed upon by most researchers. IQ tests aren't meant to measure intelligence, they measure specific cognitive functions that are tied to it.
No serious researcher honestly believes IQ tests accurately measure intelligence. Even the creator stated this application is bullshit.
“The scale, properly speaking, does not permit the measure of the intelligence, because intellectual qualities are not superposable, and therefore cannot be measured as linear surfaces are measured.”