The chance of a single cell evolving by chance into life is about one in one trillion. The chance of that single cell evolving into sentience about one in one trillion. So a trillion times a trillion = one sextillion. Divide 40 billion by one sextillion = .000001% chance that life exists elsewhere in our galaxy. Not likely - we are the lottery winners at least here in the Milky Way, maybe in the entire Universe.
Yes, delving deep into to such complexity makes it seem very unlikely and even less so that we’d be able to discover it. I do suspect there is life out there somewhere, though not nearly as confident we will ever discover, much less, connect with it.
Huh? A cell, by definition, is already alive.