At least one counter-example: https://en.wikipedia.org/wiki/Hangul is technically an alphabet, and is non-Canaanite derived.

It wasn't directly cribbed (unlike Western alphabets), but given that Hangul was invented in the 1400s after exposure to Western alphabets, most scholars still consider alphabets to have only been invented once [1] and then copied, much like the wheel. Although I suppose that's true of Cherokee too!

1: https://en.wikipedia.org/wiki/History_of_the_alphabet

It's not quite in the same category, but there's also Zhuyin Fuhao:

https://en.wikipedia.org/wiki/Bopomofo