The reason you don't understand vim is that you don't grok vi.

2.7 million people have visited Stack Overflow to learn how to exit a text editor. The most feared tool in computing is also the most elegant. A 50-year-old proof that designing for constraints produces tools that outlast the constraints themselves.

Rethinking Vim as a tool for writing. Contribute to preservim/vim-pencil development by creating an account on GitHub.

A multibyte fork of the nvi editor for BSD. Contribute to lichray/nvi2 development by creating an account on GitHub.

Learning Vim and Vimscript doesn't have to be hard. This is the guide that you're looking for.

POSIX specification for the vi text editor

Learn Vim Progressively
Über leet use vim!

tl;dr: You want to teach yourself vim (the best text editor known to human kind) in the fastest way possible. This is my way of doing it. You start by learning the minimal to survive, then you integrate all the tricks slowly.