Barring exceptions (e.g., Japanese), all modern-day alphabets, abjads, abigudas, and syllabaries -- as diverse as Latin, Mongolian, Telugu, Arabic, Tibetan, and Thai -- can be genetically linked to the Mid-Bronze Age script in the 2nd mill BCE (itself inspired by Egyptian hieroglyphs). But why and how do written letters change at all?

Spoken languages, much like the proverbial river, are fated to always be evolving, morphing into new ones (such that no language is the same centuries in the future, e.g., English). Writing systems, however, are ostensibly much more preservable (e.g., Latin alphabet). Written letters literally etch themselves into history for all progeny to see and imitate. So why do they change at all? Why is this question written with Latin (a bit amplified), but not with Phoenician? Whose idea was it to pick up that side-ways A and set it firmly on its two legs? And what precipitated the drastic changes that gave rise to the likes of Devanagari from Aramaic?