You're stuck on a desert island with 100 people and 1000 units of currency, who gets the money?

Whoever does the most work gets the most in return for the exchange of the work that benefits everyone else. People have to work together to survive and if they aren't contributing then we'd keep em alive but they should be pulling their own weight for their own survival and community.

The currency would be worthless until there were commodities to purchase. Money only has value as a unit of exchange because we all agree to collectively recognize it as representing a certain amount of labor or materials. The people would first have to organize and build up enough of a society where some of them could specialize in certain tasks, with enough people where they would need a way to reduce their labor to a universally trusted medium.

If everyone knows everyone else, you don't need money, you just negotiate every exchange. Money is only necessary when you don't know who you're dealing with.

No-one gets anything, the 1000 units get spent on a water pump and digging a well. Anything left goes on seeds for growing food and tools.

Anyone who tries to threaten or steal or seize power gets thrown in the sea for the sharks.

Only an idiot would be worried about currency. With 100 people, band together for survival. A desert island likely doesn't have a walmart... (I know what this is, but it is a silly proposition)