从 is simply two people 人, one walking behind the other — following. The oracle-bone form shows exactly this: two figures in single file. From 'follow' it became the preposition 'from': the point you set out following.
从 starts journeys: 从北京到上海 (from Beijing to Shanghai — the 从…到… pattern that maps every route), 从早到晚 (from morning to night). As 'follow' it survives in 服从 (obey) and 从来 ('all along' — 我从来没去过, I've never been). Two little people walking in file quietly power half of Chinese's directional grammar.
Two people 人人 in single file — FOLLOWING, and the place you set out FROM.
Stack three people instead of two and you get 众 (crowd) — Chinese arithmetic: 2 people = follow, 3 people = masses.