The oracle form of 為 astonishes: a hand leading an elephant — ancient China really did put elephants to work in the Yellow River valley, and 'making an elephant labor' became the verb 'to do, to act'. The simplified 为 keeps four quick strokes of that ancient work scene.
为 splits by tone: wèi is 'for' — 为你 (for you), 为什么 (why — literally 'for what?', the toddler's favorite weapon). wéi is 'to be/act as' — 成为 (become), 认为 (consider). 为什么 is among the first phrases every learner masters, and 因为 (because) is its eternal answer. A hand and an elephant, still asking and answering why.
A hand working an elephant — doing things FOR a purpose.
Elephants roamed ancient central China — the character 为 is fossil evidence of a workforce long vanished north of the Yangtze.