think intelligence as a protective mechanisms in animals, some have horns, some have teeth some have shell they can hide in, and some have better understanding of surroundings and Better pattern recognition to survive in predatory world. when you see it as a qualitative feature rather than quantitative one, then things make more sense. statistically it's very possible for millions of living things to exist in this vast universe, but it's quite improbable for them to have intelligence. just look around the species we coexist with. they're all aliens with most of them having very low intelligence. the most intelligent of them are our close descendants, monkeys. and our closest descendants don't have nearly as iq as us which just tells us that intelligence is not necessary for living beings. so there are definitely aliens around us, but we can't see them because they can't make a significant change to their planet so we could notice them. i think scientists should look for the planets with continuously changing atmosphere because intelligence is only "adoptive" protective mechanism that can get a species through constantly changing atmosphere