Not sure whether I count as a computer scientist, I only have a math teacher masters and half an information engineering degree, I dropped out.

Even knowing graph theory and understanding git I still don't have the shortest idea what https://eagain.net/articles/git-for-computer-scientists/git-... this even wants this to be.

A tree can point to other trees, making them subdirectories. A tree can point to blobs, making them files in that directory. File name, mode and such metadata is a property of the edge, and blobs themselves are nameless containers of bytes.