[Herodotus38]

I agree they probably knew more medical information, but how much of it was correct…

There’s the famous cliche of the medical students first lecture. (Paraphrasing) The professor goes up and says “Fifty percent of what you learn here will be found to be wrong in 20 years. The problem is we don’t know which 50%.

Read about the history of cancer research and its various themes as to the origin of cancer as a great look into just one subset of medicine.

EDIT: Another great way to see the errors of the past is to read wikipedia articles on American presidents and read how they died. Their final diagnoses and treatments are often vague and shocking (respectively) and often people are wondering if they would have survived if they hadn't been attended to by physicians of the time, which were probably the most well-renowned. For example, Zachary Taylor or George Washington.