I use the mouse plenty myself, but a few shortcuts have become habits. You don't need to learn that many to find them useful. Things like moving between words or selecting a whole line come up often and are mostly universal across apps and operating systems.
I think most people just get used to doing things with the mouse. Learning shortcuts takes a bit of effort, and looking through a cheatsheet doesn't help much if you don't use what you've learned right away. I wanted to make something where you could practice them as you go.
That's why I built Shortcut Express, a small desktop app that teaches shortcuts for everyday tasks. You practice them in a simulated text editor, browser and other familiar parts of an app.
Completely free and open source. Available for macOS, Windows and Linux.