This is an exhaustive list of things that are assumed true/false by many people. There are definitely dozens on the list that I was uncertain about. Here are a couple examples:
While modern life expectancies are much higher than those in the Middle Ages and earlier, adults in the Middle Ages did not die in their 30s or 40s on average. That was the life expectancy at birth, which was skewed by high infant and adolescent mortality. The life expectancy among adults was much higher; a 21-year-old man in medieval England, for example, could expect to live to the age of 64.
Napoleon Bonaparte was not short. He was actually slightly taller than the average Frenchman of his time. After his death in 1821, the French emperor’s height was recorded as 5 feet 2 inches in French feet, which in English measurements is 5 feet 7 inches (1.70 m). He was actually nicknamed le Petit Caporal (The Little Corporal) as a term of endearment. Napoleon was often accompanied by his imperial guard, who were selected for their height—this may have contributed to a perception that he was comparatively short.
Take a few minutes and read through the article, it’s very interesting!