[coldtea]

>Over the aeons they have almost certainly been part of some living creature.

There are neither enough aeons (10-20 billion years of universe), nor enough living creatures for that.

>There’s only a finite supply*

Finite supply doesn't mean all possible permutations have happenned. It's also not like an infinitely old universe (and even one like that wouldn't necessarily have permutations of molecule arrangements where thats statement is true).