IMHO anybody who says we are alone hasn't comprehended the scale of the universe.
It's unthinkable that there isn't life elsewhere on the almost uncountable other star systems. Unfortunately I think we may have also proven that interstellar travel is effectively impossible thanks to the Fermi paradox.
If the info we have is proof that no species in history could do any of the things that would let us notice them, then it can't also be strong evidence that they must exist.
It's unthinkable that there isn't life elsewhere on the almost uncountable other star systems. Unfortunately I think we may have also proven that interstellar travel is effectively impossible thanks to the Fermi paradox.