The answer is: don't ask that kind of question here. It's off topic. We even have an off topic close reason specifically for that kind of thing:
Questions asking for help identifying a game, whether based on a description, or feature list, or any other set of criteria (i.e. "What was the first game to…") are off-topic
Ok, maybe not specifically for this, but there are a lot of things that are off topic here and only finite customizeable reasons to describe them all.
Asking "what was the first game to use F5 to save", or even "how did using F5 for saving come about" is an extension of this. We're good at mechanics, and we do story, but we don't do development, identification, or the history of specific mechanics.
So there is no on-topic way to ask this question. It might be fun to research and find the answer, but Arqade isn't the place to do it.
As a side note, the WASD question you linked should probably also be closed for the same reason. It's old-ish, and sometimes things slip through the cracks. I won't mod close it this instant, but if there's agreement around that, I won't object.