零 originally meant fine, scattered rain — 雨 the rain radical over 令 for sound. Scattered drops became 'fragmentary, odd bits', and odd-bits became the mathematical zero when China needed a character for it.
零 is how you read phone numbers and years aloud: 2008 is 二零零八. 零食 ('scattered food') is snacks — the delightful logic that snacking is eating in fragments. 零钱 is small change. China used a blank space, then a circle 〇, and finally 零 for zero; today 零 and 〇 coexist, one formal, one quick.
Rain 雨 scattering into countable drops — down to ZERO.
零食 'zero-food' = snacks: eating that officially doesn't count.