All panspermia discussions strive to avoid being seen to duck the difficult question : how did life first
originate anywhere? Even if you prove beyond doubt that Sol organisms are derived form (e.g.) Van Maaanen's Star organisms, as are Banardians and
... you still have the problem of finding out how originated the first time.
While OOL (Origin Of Life) is by no means a settled question on Earth, we do at least have good evidence of what happened here. Otherwise, being able to determine that life originated in a cluster which got destroyed 3 billion years ago by a GRB is unlikely to leave much tangible evidence.
If it can happen anywhere, it could happen repeatedly. And so multiple civilisations is my bet, and they just learned to keep quiet around the Primitives.
Everyone is dead, or elsewhere remains on the list of possibilities.