People have always got sick so have always needed doctors. But while most doctors tried to help their patients sometimes their methods were weird disgusting or even dangerous. Yet this was how modern practices began.
Noses were rebuilt by attaching the skin from an arm
The first blood transfusion was between two dogs
The ancient Chinese immunized against smallpox with powered pus
If you're not too squeamish you'll see barbers doubling up as surgeons leeches drawing out blood and corpses being dug up so doctors could study anatomy - along with the first anaesthetics to remove pain one of medicine's great miracles.