Don’t listen to people who say it’s not possible to have fun learning about this stuff. It can be. I can be boring, too, depending on your interests. Sounds like you’re worried about wading through things like Capital, Communist Manifesto, etc. Totally warranted – they were written in a different time and for a different audience. That’s not to say that there isn’t good stuff to get out of primary sources, but it’s more difficult.

I recommend listening Karl Marx: A Nineteenth Century Life to get some context as to who he was, what movements he was a part of, the state of the world he grew up and lived in, and a breakdown of the things he believed, things he changed his mind on, etc. It gives you important context. You don’t need to slog through it or do a ton of mental work. Just listen and absorb it. If you don’t understand a section, replay it and try to do some mental work to “get it,” but if it doesn’t click, move on and keep listening. Over time, you will begin to understand.

I also recommend listening to Michael Parenti’s Blackshirts and Reds. Very accessible.