It was almost certainly spoken around a fire in a cave and has been lost to time before humans really recorded history
Cave fire speech is not a medium in the strict sense, though.
That means at least writing would have to have been available.
Gilgamesh epic might be a good candidate, I think.Spoken word is indeed a medium in the strict sense.
The Celt tradition being a prime candidate for that sort of thing (if you are interested in an attempt to consolidate the Irish oral tradition I highly recommend George Green’s “Hound”).
Gilgamesh might be a good candidate for the first probable one though, as the oral tradition is almost impossible to prove.
Alongside that I’d argue certain bits of the old testament feel like villainous monologues.
Not a real monologue, but Humbaba mocks Gilgamesh and Enkidu for their hubris and lack of wisdom. He specifically attacks Enkidu, questioning his origins and his betrayal of the wild. He vows to slaughter them both and feed their flesh to the birds and beasts of the forest.
The oldest in English that we have access to might be in Beowulf? Villain monologues are as old as stories, and stories are as old as humanity.
Judging from prose like Mobi Dick, it was written at about the same time, covered 10+ pages, had 342 commas and semicolons, and was a single epic run-on sentence.
Cave drawings?
Richard III starts with a villain monolog.
Oh dear Richard the 3rd
I would check the bible, it’s full with that kind of stuff.
Isn’t there several in the old testament?
