It seems rather strange that a species as advanced as the Jjaro could not prevent the extinction of a favored client race, especially given that human cloning is now only a matter of "when", and cloning can be done with at least a little success (most of the time defects appear, but not always).
Ergo, something not in the genome AND non-recreatable made them the Pythia. I've decided it was some sort of racial consciousness, psychic or otherwise. Unable to recreate it, the Jjaro left representatives of a less-evolved form of the Pythia on two remote planets and hoped they would re-evolve.
One was Argos, one was Earth. Humans have been on Earth a lot longer than we think, but tragic setbacks of our own making have held us down (technologically and evolutionarily).
It's as good an explanation as any
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Formerly-Rampant Human-Coded AI