Well, Ötzi (* 5,000 BCE) had cavities. I think you’d need to go back to before the Neolithic Revolution. Shipwrecked sailor Steven Callahan also noted in his bo

Well, Ötzi (* 5,000 BCE) had cavities. I think you’d need to go back to before the Neolithic Revolution. Shipwrecked sailor Steven Callahan also noted in his book “Adrift” that, after 73 days adrift at sea eating nothing but fish and sea birds, his teeth and gums were healthier than ever before. So there’s something to your argument.