I started writing some Dad joke about a mystery being wrapped in an engima but it fell flat.
This post did however prompt me to read a bunch of different articles about the origin of the QWERTY layout, and it's debated whether the layout resulted from a desire to deliberately slow down typists to prevent keys jamming, or whether it was actually iterated and optimised over time. It does seem clear from my reading that the keyboard was not designed with first-time users in mind, but existing typists, so that may explain the "of course that big one is the space—it's so obvious it doesn't need a label".
I suppose it's one of those things that has a very short learning curve. You only need to hit it once to discover what it does, and then you've got it.