yeah... i play a lot of games with crafting trees and very often there is basic ones where there is one common material and once you have this thing made from it, there is a dozen things you can make after that.

so you could say that PoW only has one use: making bitcoin, and then with bitcoin you can make dozens of things (millions lol). including network security by raising the opportunity cost for an attack.

yeah, paper could be another example. you can make it out of stems of many kinds of plants, but then with paper you can do shitloads of things, writing, starting fires, origami, even clothing (that's kinda upstream on the skill tree from origami i guess).

proof of work is probably more like fire though, and the most productive use of fire is refining metals. which is a neat analogy.