At some point old notation gave way to new notation.
The unit note of contemporary music is the Semibreve, and the half note, the Minim. Both words mean short (and shorter) time duration.
Early music had: the Long, the Breve, and the Semibreve.
The Semibreve being the shortest note, whereas now it is the longest.
Both systems were binary: ie each succeeding note was half the preceding note.
My theory is this: With the invention of movable type used in printing presses the dies for the Long, the Breve, and the Semibreve would have become clogged with ink very frequently. Far better to have dies with solid surfaces like the Crotchets, Quavers, and Semiquavers etc., with only the occasional Minim and Semibreve.
In short, has the change from long notation to short notation been precipitated by the invention of the printing press?
Or is there another explanation for the change in notation?