What does "Seeded" mean in the context to Ancients seeding human life across the galaxies?

So in the Stargate Universe, The Alterans are the origin of all human life across the cosmos. They spread across their own galaxy, then eventually the schism happened that split them into Ori and Ancients. The Ancients then escaped to the Milky Way Galaxy, where they settled many worlds, most notably Terra (Earth), and "seeded" human life across this Galaxy and eventually The Pegasus Galaxy.

But what does "Seeded" mean? my original interpretation was that they cultured the natural life on a world like Terra and Humans (IRL us) evolved naturally from this seeding, related but not directly to the ancients.

On my recent rewatch, both SG1 and Atlantis seem to lean more to that present day Humans (those descended from Earth or Atlantis in the Pegasus Galaxy) are Ancients that remained and effectively devolved from the higher evolved state that the Ancients had achieved (I don't mean ascension, I mean their biological state) and regressed culturally to hunter gatherers by the time the Atlanteans returned to Terra 10,000 years ago.

So whats the general opinion on what this means? I think my general confusion comes from the IRL explanation for humanities evolution from primates, who definitely do exist in the Stargate Universe. Are Primates related to the Ancients? or is it simply in this setting that the IRL theory of Evolution is simply incorrect?