None to add to that, though I was more thinking (as another child post) of poets and thinkers who were clearly self-referentially aware of what they were doing and what was going on generally with literary narrative (Swift and Coleridge come to mind).

Edit: oh that child post was you :). Yeah there was for sure a gaping lacuna before Chaucer, and even then you may be right that there was nothing as explicitly on the nose until the 20th century.

TV tropes and Mr Smithsonian are still late to the race in the scheme of things but nearer the pointy end than my original post may have given credit.