There's a well-articulated essay from Christopher Olah that captures the undercurrent, and perhaps even the motivation of many of these papers https://colah.github.io/posts/2015-09-NN-Types-FP/

You're completely right that the repo doesn't promote any introductory material. CT is notoriously difficult to get into, and this repository wasn't meant to be a pedagogical one, but rather a list of all the relevant papers.

Though, I'll see about remedying this. I have a different repository that curates a list of (what I consider to be, as a CS major) relatively approachable CT introductory materials https://github.com/bgavran/Category_Theory_Resources

and it might be a good idea to add a pointer to it.