Succeeding at intelligence tests is not the same thing as succeeding at survival, though. We have to be careful not to ascribe magical powers to intelligence: like anything else, it has benefits and tradeoffs and it is unlikely that it is intrinsically effective. It might only be effective insofar that it is built upon an expansive library of animal capabilities (which took far longer to evolve and may turn out to be harder to reproduce), it is likely bottlenecked by experimental back-and-forth, and it is unclear how well it scales in the first place. Human intelligence may very well be the highest level of intelligence that is cost-effective.