If you lump abjads and alphabets together, the Ugaritic alphabet represents another invention of an alphabet. Instead of being derived from Egyptian hieroglyphs, it's derived from cuneiform. Old Persian cuneiform, another invention, is also largely alphabetic, with only 9 of the 22 consonants being routinely written in forms that also include a vowel.
I love the origin a story of the alphabet. Ancient Egypt used hieroglyphics to write ideas and concepts but eventually created a more efficient script called demotic.
Traders or miners from Phoenicia visited Egyptian quarries and saw this squiggles on walls. They decided to just use some of the characters to represent sounds and not concepts as the Egyptians were doing.
Ancient Egyptian scripts before Coptic represented both sounds and concepts. But mostly sounds. You'll see 𓅓 used a lot in hieroglyphic texts. It's not because the ancient Egyptians loved to write about owls. It's mostly being used for its phonetic value, "m", which is usually a preposition, but can also be used to spell larger words.
The innovation of proto-Sinatic script, which was the ancestor of Phoenician script, was less going purely phonetic and more simplification. Ancient Egyptian scripts before Coptic used symbols that could represent a series of consonants. For example, 𓆣 represents the consonants "ḫpr" and 𓉐 represents the consonants "pr". There were symbols that represented single consonants, so you could potentially write just 𓐍𓊪𓂋 instead of 𓆣, although the Egyptians usually didn't do so. (They would sometimes write 𓆣𓐍𓊪𓂋 for "ḫpr" as a phonetic complement.) But that's what happened with Proto-Sinatic. The result was that instead of having to memorize hundreds of symbols, you had to memorize twenty or so. Much easier to learn, although you did jettison mechanisms to disambiguate homonyms.
Hieroglyphs and Hieratic were the first forms of Egyptian writing, apparently developed simultaneously. Hieroglyphs were mostly used for monumental writing, but sometimes on papyrus. Hieratic was a cursive form of hieroglyphs that could be quickly written with a pen. Demotic is an evolution of a form of Hieratic used in the north.
