"Control-C sends SIGINT" has been a standard for longer than "Control-C means copy".
I blame Microsoft.
(I still have a few Windows apps we use at work that use these standards; good to know they actually were a standard.)
Copy and paste are also in the right-click menu, and the keyboard shortcuts are shown there.
> (Or should my games have used hjkl)?
I still play a game that does...
How do you quit man? How do you quit less?
'q' to quit is pretty standard in the TUI world.
As for if you stuck in insert mode, this is more akin to when you have text highlighted in a GUI editor, the shortcuts change because you're in a different mode.
Remember all editors have modes, vim is just a bit more in your face with them.
The <esc> at the beginning is only necessary if you've already got into insert mode. That said, it'll not do any harm.
Discoverability is another problem. You can have weird keyboard commands, but make it possible to find them without searching stack overflow. I miss when applications had a big bar at the top of all the commands you could do and their keyboard shortcuts. I'm on chrome right now, and copy and paste is hidden away in a menu. And the keyboard shortcut for it isn't mentioned. How do you think people learned the keyboard shortcut in the first place? Or apple phones have a bunch of gestures that are useful, but no one knows about because you can't discover them.