Left person radical 亻 - the side-form of 人. Anchors 份 in the human-action family alongside 你, 他, 价, 仅. Carries the meaning core: a 份 is what falls to one person - their portion, their share, their copy.
Right component supplies the sound: 分 fēn → fèn (just a tone shift). Adds a perfect semantic match: 分 already means 'divide,' so 亻 + 分 reads transparently as 'a person's divided share.' Same phonetic in 纷 (numerous), 粉 (powder), 盆 (basin).
