Certainly it’s possible to be a Linux user without learning the things that we would say mean you “know Linux”, but I think the most effective way to learn them also requires being a “user”. Using Firefox on Ubuntu instead of Windows doesn’t teach you Linux, but If you don’t have X11/Wayland and a browser and you can’t do your online banking and social media and Youtube, then you won’t actually learn the “real” stuff, because you’ll spend all of your time in Windows and Linux will feel like homework. Instead, get a full Linux desktop experience that you can do all the things you want to do with, and as you’re doing those things, also seek out opportunities to learn the shell and userland utilities, etc.