Chimps, gorillas, and humans are very close in the genetic tree, but cannot cross-breed. For a high level of genetic compatibility, constant contact and cross-breeding are likely required.
That seems to apply to the Star Trek one, which going by the lore seems to be more of an artificially maintained rotten stump that had any potential for divergent/adaptive growth preemptively cut.
The Star Wars lore you link only seems to talk about empires that made contact with multiple species and might have helped spread them over a hundred thousand year span. It does not seem to mention a single point of origin or an artificially crippled evolution that would enforce parallel development.
