[meepmorp]

Hieroglyphics weren't really ideographic after a very early point, because it's a pain in the ass making up new symbols for every word. Very quickly, it transitioned to being largely an abjad, representing only consonants. Abjads work reasonably well for semitic languages, as the consonantal roots of words carry the meaning and a reader would be able to fill in the vowels themselves via context.

According to the account I've heard, it's the greeks who invented the alphabet, by accident. The Phoenician script used single symbols to represent consonants, including the glottal stop (and some pharyngeal consonant that would likely be subject to a similar process, iirc). The glottal stop was represented by aleph, and because Greek didn't have contrastive glottal stops in its phoneme inventory, Greeks just interpreted the vowel that followed it as what the symbol was meant to represent.

It's a bit of a just so story, but also completely plausible.