Unlike the age we live in today, in our more civilized time, we used to bury our dead directly in the earth. We send the body right back to Nature, where it is originally from. No such thing as an overpopulated cemetery every existed for us. Our burial grounds were recyclable. After a few years, we were able to use previous burial spots to bury new dead.
The reason it was possible for us to do this is due to having one specific piece of knowledge, which is our understanding that bones decay. In a matter of about 10-12 years, the only thing you may find left of a buried body is their skull and hair, everything else gone. The skull may take a longer time, but it surely won’t take the microorganisms more than a hundred years to completely decompose it.
Given this reality, we must now ask the obvious question. How is it possible for scientists to find bones buried in the ground for thousands of years?
Bones are not plastic; they are biodegradable, which means they decay. Everything in Nature that suffers death decays. It’s a natural part of the cycle of life.
The only time bones are preserved is if it is done intentionally, like in the process of mummification. Otherwise, any bones that are exposed directly to Nature without any artificial interruption will certainly decay. Maybe the bones they are claiming to have discovered are simply the ones they put there. Maybe the evidence they found are the ones they created.