That’s a red herring. Ex post facto the activity of language use as a construction must supersede some enaction by capable actors.

This is a complete tautology in terms, and any dispute must therefore be over the ontology in which it is expressed. To elaborate how something came to be is not required to express that something is.

What makes capable actors capable in the first place is not derived from thin air. There's a reason a capable actor came to be where there was none generations prior. That reason did not come about without reaction to some outside vector.

Evolution optimized for language learning abilities before the full capabilities came. Evolution is not thin air.

The «air» is here an allegory for «large language corpus». It is self-evidently true that as we move backwards through history we eventually pass the first language utterance for any given definition of language or utterance. From here on out, the «air» is indeed «thin». There are still other things, but no «air» (i.e. «language corpora»).