We are not simply stardust…
I’ve seen that Lawrence M. Krauss “… You are all stardust. You couldn’t be here if stars hadn’t exploded, because the elements - the carbon, nitrogen, oxygen, iron, all the things that matter for evolution - weren’t created at the beginning of time…” quote being bandied about and I need to say a couple of things about why that’s not entirely true. Sorry.
Now, those elements (the carbon, nitrogen, oxygen, etc) are necessarily the remnants of some star. The giveaway for the fact the star exploded is down to the fact we find radioactive material in the earth’s crust, where it simply decays. Going back in time, these radioactive elements must have formed somewhere, and the formation of the earth was probably not violent enough to spur nuclear reactions with enough energy to produce these elements. Radioactive materials must be formed by smashing heavier elements together, for which, in the vacuum of space, those conditions only really exist when a star goes supernova. Best guess is the rest of our elemental make up (the atomic weight of iron and smaller) came from the same supernova, but hey, where you find molecular clouds, made up of stuff like molecular hydrogen and carbon monoxide, the conditions tend to be right for star formation too. Such elements could have been created in some other kind of star, not just an exploding one.
I digress… your body, by the number of atoms, is dominated by hydrogen; around ~67% by elemental abundance. Hydrogen is not created in stars - in stars, it is fused to allow the release of energy by nuclear fusion, in turn creating heavier elements. Maybe we get some hydrogen back when the star goes supernova? … putting all that explosive supernova energy back into the atoms the star has built, back into separating them into hydrogen atoms. Maybe, but not much. Basically, there has only ever been one source of hydrogen which was the creation of the universe: the Big Bang. Without a universe, there is no such entity as space-time and thus, no dimension as time. The Big Bang was itself the beginning of time.
Most of your hydrogen atoms have been around since the dawn of the universe. And sure, yes, evolution couldn’t continue without your oxygen, carbon, nitrogen, iron, etc. But the most basic building block of all life, and thus very necessary for evolution, was created some 13.7 billion years ago in the same instant that the very fabric of space-time came into being.