力 is a plow, the ancient unit of muscle. 且 lends sound and the sense of stacking. 助 is strength stacked onto someone else's effort — help as literally adding your plow to their field.
The Mencius used 助 for the well-field system: eight families 助 (jointly worked) the public plot in the middle. 互助 mutual aid remains the organizing word of Chinese villages and group chats alike — help is a verb you owe your neighbors.
Stack 且 your strength 力 onto someone's load — that's HELP.
助攻 'assist' in sports and gaming borrowed 助 — the stat for helping someone else score.