So? With (for instance) this simple & ancient technology - https://en.wikipedia.org/wiki/Slipway#Slipways_in_ship_construction https://en.wikipedia.org/wiki/S

So? With (for instance) this simple & ancient technology - https://en.wikipedia.org/wiki/Slipway#Slipways_in_ship_construction https://en.wikipedia.org/wiki/Slipway#Slipways_in_ship_const... - people can routinely construct ships weighing ~1000X the weight that any one worker (or crane) could lift.