"How did words originate? What theories chart their birth...?" In Theory or The Corey Lewandowski Approach to Language Origin: A Constrained Nonsense Rhyme

How did words originate? What theories chart their birth?

In bow-wow theory, Man apes sounds all ‘round -- for all he’s worth. 
In pooh-pooh theory, Man responds to worry or surprise
or pain or fear. (Says pooh-pooh theory, "That’s how words arise.")

In ding-dong theory, Man reverberates with Nature’s tone.
(Of all these theories, ding-dong seems most largely overblown.)
In ta-ta theory – one the linguists know as yo-heave-ho – 
Man’s tongue mimes gestures made while he hoes yet another row.

In la-la-theory, Man’s inspired by playfulness and love.
But one new theory’s superseded all of the above.
In womp-womp theory, language starts when certain soulless men
poke fun at children’s suffering. It’s happening again.