One way to get at this: making your own language will show you not only what each thing means, but also what the underlying mechanics are!
Crafting Interpreters is a great guide on this: http://www.craftinginterpreters.com
Crafting Interpreters is a great guide on this: http://www.craftinginterpreters.com
True, but if everyone who asked any question about something had to implement those things to even understand the basics of them, we'd never get anything done :)
You don't need a degree to be a developer (I don't have one) but I think it's a good indication that it is actually reasonable to think that every developer could implement a programming language. (And I mean developer as in someone who writes code professionally as their main job, not necessarily sysadmins or designers or whatnot).
To reiterate, I think many more people than think they can can develop their own language.