Japanese Manyogana does not count as a true alphabet because each character represents a mora (several sounds together), not an individual consonant or vowel.
Hangul is a bit debatable as to whether or not it is a true alphabet because. Although individual components within each jamo (the characters in hangul) do indeed represent individual consonants and vowels, they cannot exist alone and must always be part of a set of 2, 3, or 4 components. So in a sense it works more like a syllabary (the same as hiragana in Japanese) rather than an alphabet. Opinions are varied on this. Though Hangul was also very much artificially created (it wasn’t an evolution of an existing system, it was made from scratch), as Korea used Chinese characters up until then, so if we go by naturally evolving Latin/Greek is still the only one.
This is why in linguistics we typically say that Greek (and by extension the Latin that derived from it) is literally the only time humanity naturally invented a true alphabet, ie a system where consonants and vowels are represented individually and separately. All other alphabets before then were what we call either abjad (alphabet systems with no vowel indicators, like Arabic) or abugida (systems where vowels are only represented with diacritic marks, like Thai).
Japanese Manyogana does not count as a true alphabet because each character represents a mora (several sounds together), not an individual consonant or vowel.
Hangul is a bit debatable as to whether or not it is a true alphabet because. Although individual components within each jamo (the characters in hangul) do indeed represent individual consonants and vowels, they cannot exist alone and must always be part of a set of 2, 3, or 4 components. So in a sense it works more like a syllabary (the same as hiragana in Japanese) rather than an alphabet. Opinions are varied on this. Though Hangul was also very much artificially created (it wasn’t an evolution of an existing system, it was made from scratch), as Korea used Chinese characters up until then, so if we go by naturally evolving Latin/Greek is still the only one.
This is why in linguistics we typically say that Greek (and by extension the Latin that derived from it) is literally the only time humanity naturally invented a true alphabet, ie a system where consonants and vowels are represented individually and separately. All other alphabets before then were what we call either abjad (alphabet systems with no vowel indicators, like Arabic) or abugida (systems where vowels are only represented with diacritic marks, like Thai).