首先
shoǔ xiān · HSK 3
first
☝️ 首 = head/first + 先 = before/ahead; head-before = first of all
首 means head and by extension the first or top one. 先 means before or ahead in time. Together 首先 stacks two first-ish morphemes to mean first of all or in the first place, often opening a list.
首 — hair 丷 over face 自 (eye + nose)
首 is a pictograph of a head, originally drawn with hair on top and a face below (containing the eye element 目). It meant 'head' literally, then extended to 'chief, leader, first' since the head is the topmost and foremost part of the body.
先 — 𠂉 (person variant) on top + 儿 (legs) below
先 originally depicted a person with a foot or step shown above the legs 儿, suggesting someone walking ahead. From this image of going before others came the meanings 'first,' 'earlier,' and 'ahead.' The modern shape preserves the 'legs' radical underneath.