I didn't really understand your explanation so I might be restating your ideas, but just in case:
> And then - just to keep it confusing - we have to split both of those groups of five semitones, so... we arbitrarily split them as 2-2-1 (i.e. WbWbWW keys). Thus the white/black keyboard pattern, starting at C, of WbWbWWbWbWW. If only someone had explained all this in grade school.
We don't arbitrarily split them! It was very much made on purpose to match the diatonic scales, which are very natural due to being a chain of fifths. E.g. from F ascending 5ths: F-C-G-D-A-E-B-¡F!
It's not arbitrary that we based modern keyboards around heptatonic scales! Then we added some black notes so we can transpose, which is pretty convenient on 12-TET.
> And then - just to keep it confusing - we have to split both of those groups of five semitones, so... we arbitrarily split them as 2-2-1 (i.e. WbWbWW keys). Thus the white/black keyboard pattern, starting at C, of WbWbWWbWbWW. If only someone had explained all this in grade school.
We don't arbitrarily split them! It was very much made on purpose to match the diatonic scales, which are very natural due to being a chain of fifths. E.g. from F ascending 5ths: F-C-G-D-A-E-B-¡F!
It's not arbitrary that we based modern keyboards around heptatonic scales! Then we added some black notes so we can transpose, which is pretty convenient on 12-TET.