> It only takes one small group within one species to generate a self-replicating probe

And what would that probe look like?

For it to be a useful to the sending civilization, it needs to go out, replicate, and send information back.

The first two are easy. Send out lots of meteorites with bacteria on them.

The third is not so easy. Creating a self-replicating machine which can then transmit back across interstellar distances or store information in its replication program and then send more of itself out is hard.

Or, you help life evolve and then wait for the results to reach the point where they can send out their own probes and signals...