Don't feel stupid. It's bad enough that all of IT is one giant impostor-syndrome support group. There's literally too much for any one person to know, and it's been that way for a very long time. Just give it your all, and memorize how to reliably search and look things up; take notes for the really important stuff. The rest will filter into your memory with practice.

Also: anyone that holds this kind of thing over your head is attempting to distract from how much they don't know. Most people in this industry understand and don't judge.

As for the ^ thing, I recall seeing that as far back as the 1990's. I want to say Microsoft actually popularized it, but it could easily be OS2 (IBM) or Apple. In hindsight, it's kind of wild to have a TUI (terminal user interface) hold your hand like this. Nano (and Pico) are kind of in a special category like that.