We know nothing. We're just ants comparing to the whole universe, and every discovery will only prove that no matter how much knowledge we try to gather, we still know nothing.
And alien life form doesn't have to only live on some planet faar far away somewhere, I think aliens visited us, our planet, in the past. And not only once in my opinion. There were many unexplained mysteries, that were never solved , indicating it being the truth or highly possible to be one. Ofc there are many hoaxes, but not all of them have to be 100% fake, that is what I believe :) I support science reasoning mainly, but wouldn't life be boring without real-or-not-real secrets to be revealed or just thought about?