This is gonna be fun
https://blog.thjread.com/posts/2020-03-09-getting-started-category-theory.html
Currently on the chapter 5 of Bartosz Milewski's book, and gotta say, if this is the "easy" introduction, I am immensely humbled by the richness of the field.
Any single object category is a monoid though. ( This stumped be because I was staring at monoidal categories only to realize that the word 'monoid' is used as an adjective here!!! )