USS Triumphant wrote:
We seem to have seen that the Preservers spread humanity farther and wider than the other species that they seeded all over.
Not necessarily. The only confirmed Preserver-seeded world was Miramanee's planet; most of the other Earth-duplicate worlds were given other explanations, due to the lack of continuity in '60s TV. Besides, the Enterprise
was just one ship in the fleet. Who's to say the Hood
and the Excalibur
weren't encountering uncanny duplicates of medieval Andoria or Bronze Age Tellar? Indeed, we have seen some species that resemble each other unusually closely. The Mintakans are highly Vulcanlike but don't seem explainable as part of the Romulan colonization effort. And the Talarians from "Suddenly Human" seem a lot like a Klingon offshoot.