There are quite a few science fiction franchises out there (notably Star Trek) which feature progenitor species which “seed” planets with their genetic code, resulting — millions of years later — in a bunch of intelligent humanoid species who can all interbreed with each other.
That is not how evolution works.
But I’ve figured it out: Whenever a progenitor species talks about “seeding” their genetic code, what they’re actually talking about are mitochondria. We don’t realize it, but mitochondria are actually heavily designed pieces of biotech with significant subspace extrusions undetectable by modern science. They are specifically designed to tweak bipedal humanoid forms to Progenitor-style intelligence. When Progenitor-style intelligent species mate, the mitochondria are also responsible for making sure that viable offspring are possible.
Hmm… that’s technobabble? Yeah. Welcome to Star Trek.