Why do people assume alien life would be intelligent? Intelligent life is extremely rare on earth and has only occured for a brief moment in its history due to highly specific environmental scenarios at the time as well has historical events. If we didn't get that meteor that wiped out the dinosaurs, mammals would probably still be shrew like creatures as they were for millions of years until mass extinction exposed new ecological niches. The great oxygenation event could have easily killed off all life on earth too. Most of the biomass on earth today comes from plants, famously unintelligent and sessile, commonly using strategies that favor spawning thousands of offspring that have random mutations, with a few who go on to survive in an ecological niche.

If we use our own earth as a model, alien life is far more likely to be unintelligent. Its a big human bias to assume that if there were intelligent life out there, it would even think like human life, so our abstractions such as mathmatics and physics will probably look entirely different when a completely different mind formed from a different evolutionary trajectory encounters natural phenomenon and attempts to make truths. Even with our own species it took us millions of years to establish our current truths about what we consider true. This begs the question, if in millions of years we will consider our current abstractions that interpret physical laws of the universe to be just as worthless as past interpretations for these same physical laws that we used as truths in centuries previous.