>>510149296 (OP)Alone isn't correct, drifting in a period of time with a vast evidence of not much else going on is more accurate.
Think of human history as we know it and how many "eternal" Empires have risen and fallen just in that very narrow fingernail's width of all habitable time in the universe.
Its entirely possible for intelligent civilizations to completely miss each other just due to the vastness of time alone, its not that there are no other intelligences, its just that what may be left of them is some kind of data archive on a long dead planet, and by the time another intelligence arises to wonder if we're here, we'll all be data engrams inside some AI constructed Boltzmann Brain that doesn't care much about the rest of the universe other than to travel through it and consume all the data it can.
We're not "alone" we're not "unique" we're just on an island in time where there do not appear to be other people on the same island.