Are you trying to claim that Chaucer used "they" as a gender neutral singular pronoun? That is extremely dubious considering that half of the Middle English speakers were still using <he> as the third person plural pronoun[1] (descended from Old English <híe> and unrelated to the third person masculine pronoun). Chaucer himself alternates between native Old English and Anglo-Norse forms depending on grammatical case and/or whim[2].

[1]: https://en.wiktionary.org/wiki/he#Middle_English-they [2]: https://sites.fas.harvard.edu/~chaucer/pronunciation/gr.html...