Survey: Is the Earth old enough to say that we live off of the mortal remnants of our ancestors?

When we exhale, we are removing carbon dioxide and water vapor from our bodies. The carbon dioxide is made up of carbon and oxygen atoms some of which were parts of chemical compounds created by our own bodies. The same is true of some of the hydrogen and oxygen atoms that make up the water vapor. Some of the carbon dioxide and water that we release is taken up by plants that are consumed for food by other humans, or the plants are consumed by herbivores that are consumed by humans. So it is correct to say that some of the atoms in our bodies had previously been parts of the bodies of other people.