Almost certainly there is more life out there somewhere. But if the level of rarity is “for every billion years, it happens once in every thousand galaxies” rare, then unless FTL travel is real humanity will probably never get to see it. And until we see a second example, we can’t begin to calculate the level of rarity.

But it’s also not like we’ve looked at enough of our galaxy to say it’s rare either. We just don’t know.