I think we agree that language developed over time and is not inborn but learned, possibly beginning in utero.
Chomsky and others believe the structures of language and deep grammar are hardwired.
Babies will also babble every known phoneme before weeding out the ones not needed for their culture's specific manifestation of language.
Much as I enjoy discussing the birds and beavers, I think we're over-generalizing Lucretius's analogy. I think he's really only just using the analogy of building a structure - without a blueprint/plan/exemplum you can't build the structure *if you're a human or god (the analog of a human)* Nature on the other hand has no need of a plan because the whole of the cosmos is unplanned. Atoms come together. Atoms come apart. Various things arise. Various things don't arise. There is no plan... But isn't it grand that we, birds, and beavers exist and that we can take pleasure in our and their existence.