We’re working with an n of 1 basically. If you’re talking about the drake equation, many of those terms are wild estimates that we simply don’t know the answer to, it’s more of a thought experiment. In the course of astronomy history when we’ve assumed uniqueness about earth or our cosmic situation we’ve generally been wrong. Unfortunately the vast distances between stars make an estimation of life in the universe difficult with current technology, as there is so much we can’t observe.

But there’s billions of stars in the galaxy, billions more planets, and septillions of star systems in the universe with billions of years for life to happen. Intelligent life has happened at least once because we’re here. Even in the tiny slice of planets we’ve been able to observe in some way in our narrow little corner of the galaxy we’ve found numerous ones in the “goldilocks” zone. It would be utterly shocking if we were the only intelligent life out there, even more shocking if our planet had the only life. And all of this assumes we know what kinds of life are possible! We’ve only ever seen our own type of chemistry.

Don’t mistake this for me saying we’ve been visited by aliens in UFOs or something though, not saying that at all.