I previously thought that the “case” in upper-case was the case that means “situation”, “state”.
Turns out that it refers to the physical cases (boxes) used by compositors. The majuscule types were arranged in an upper case, the minuscule in a lower case.
I also would probably have figured that the case=situation and case=box were ultimately shades of meaning of a single word. After all, it seems a small semantic leap from one to the other.
But it happens they are separate words with separate origins. The first is from Latin casus meaning situation, and the second is from Latin capsa meaning receptacle.
So much to learn.