I remember first encountering classes. I simply could not understand what they were from reading the documentation. Later, I picked op Bjarne's C++ book, read it, and could not figure out what classes were, either. Finally, I obtained a copy of cfront, which translated C++ to C. I typed in some class code, compiled it, and looked at the emitted C code. There was the extra double-secret hidden 'this' parameter. Ding!…
As an engineer in the forties it is somewhat encouraging to read that you felt the same way even if it was about different topics.
For me, these days it is about frontend generally, Gradle on backend and devops. So much to learn, so little documentation that makes sense for me. (I'm considered unusually useful in all projects I touch it seems but for me it is an uphill struggle each week.)
I always win in the end even if it means picking apart files, debugging huge stacks and a whole lot of reading docs and searching for docs, but why oh why can't even amazingly well funded projects make good documentation..?)