Why don't *you* explain in more detail what you meant by your opening post.
Before you go further, a few points.
It's energy, not mass, that is conserved. The fundamental concept that underlies atomic bombs and nuclear power is that mass is a form of energy. Mass can be converted to some other form of energy, and quite a bit of energy.
However, the change in mass in a typical chemical reaction is negligibly small. You can pretty much ignore that mass is not a conserved quantity. Let's take it as a given that mass is conserved.
We are born small, eat and drink (a lot!), go to the bathroom (a lot!), and grow, but eventually we all die. Nature recycles our mass. That's what Simon meant by "ashes to ashes, dust to dust".
One last point. This site is not the place for speculative conjecture. Just don't go there.