OP here. I personally had a lot of trouble when trying to learn category theory on my own. Part of the reason for this is that the need for category theory come

OP here. I personally had a lot of trouble when trying to learn category theory on my own. Part of the reason for this is that the need for category theory comes from a lot of other abstract mathematics being unified under the category theoretic lens. I didn't have much of that background my first few times, and I think that was one of the major reasons I didn't succeed in understanding it. After a few years of graduate school, with lots of colleagues working on the same material as me, it has gradually become much easier. The best text I've seen so far is Paolo Aluffi's "Algebra: Chapter 0". It's an algebra textbook meant for first year graduate students in pure mathematics, but it was the major factor in clarifying category theory for me. Of course, the book also contains pretty much all topics in abstract algebra from basic groups to abelian categories. So if you're not pegging to be a research mathematician, chances are the book is not worth your time. Part of my goal with this series is to demystify the subject as it was demystified for me, and to incorporate as many concrete applications to programming concepts as I can. I hope you find some value in what I produce :)