Rare Earth hypothesis, that's your answer.
It's nearly certain that we are alone in this galaxy, unless there aren't any mechanism in the universe which promote abiogenesis. Our biological history suggests that life, especially intelligent life, is an extremely rare occurrence. Given that galaxies are uninhabitable for the most part, aka galactic habitable zone, the numbers are actually quite unlimited, especially when considering that theories about alternative biochemistries have been blown the fuck out recently. The current knowledge supports that water and carbon are the best elements for life. That filters a lot of planets out of that 10%, then you probably need a suitable planet and our solar system is in a way unique, so is our Earth if you truly look at it. Then all you need is abiogenesis, which is most likely extremely unlikely event even when there's all the perceived elements involved. Next, you need that abiogenesis to lead to intelligent life which is probable highly more unlikely event chain that abiogenesis.
I'm very convinced that if there's intelligent life out there, they're most likely that far away that we cannot possibly ever encounter each other. I wouldn't say that it's impossibility that we are the most advanced beings in the whole universe either. People tend to take life as something self-explanatory, but it's truly not and this thinking comes out of survivor bias.
I'd say that if alien life was common on another planets, it would suggest some form of creation. It would have to mean that universe has some type of mechanism which promote life and abiogenesis. It would be absolutely ridiculous to think that that the universe has such mechanisms for no reason whatsoever.
