According to the Law of Conservation of Mass, matter can neither be created nor destroyed. This means that all atoms are recycled over time. Which in turn means that our own atoms are ancient as well. One’s skin could have carbon in it from a meteorite or from a trilobite thousands of years old, and your blood could contain hydrogen from earth’s original atmosphere.
a fun game to play is “guess whether the screaming children outside getting murdered or just playing” and you’re not allowed to look you have to guess blind and you have to watch the news to see if you were right