先祖
せんぞ · senzo · JLPT N2 · noun
ancestor
先 (first) + 祖 (ancestor): the first ones who came before you, your forebears
先 means 'before' or 'earlier', and 祖 means 'forefather'. Put together, 先祖 names the people who came before in your family line.
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.