Oracle-bone 行 is an aerial view of a crossroads — four ways meeting. Everything it means flows from there: going, movement, a road, and (read háng) a row or a trade — the shops lining the street.
行! is the all-purpose Chinese 'OK, works for me'; 不行 is a flat no. 行 read xíng moves: 自行车 bicycle, 旅行 travel, 飞行 flight. Read háng it stands still: 银行 bank, 行业 industry. 你真行! means 'you're really something!'
A crossroads — where GOING happens; if the way is open, it's OKAY: 行!
三人行，必有我师 'when three walk together, one can teach me something' — Confucius's most quoted line about humility, built on 行 as walking.