This is the closest thing to a teleology I believe in (some of the time). Why do anything? Because the aliens are coming. (I literally think of it using the same verb as you.) And then, death match time. Which may well get settled by utter luck, as likely happened in old world vs new world. But still. The more divergent two populations are, the less likely their meeting is to result in cohabitation. I don't think it's luck that there's only one remaining sentient species on the planet.

See also this excerpt from Peter Watts: http://akkartik.name/post/2012-11-21-07-09-03-soc

Not so outrageous though; think most scientific inclined people find this statistically and otherwise viable.

Yeah. Odds are that we are aliens.

Meaning: some alien life ( bacteria) landed here on a comet and evolved.

The Fermi paradox says otherwise.

When? In 2022? That would give me something to be excited about.

There is nothing alien. If from another planet, it makes no different. We are all part of the whole of the universe or universes. We Are One!

Protomolecule?