Couple of points on life expectancy: If you made it to age 15, it was likely you'd live to be 60-80. Life expectancy wasn't lower in the past because people died earlier, they just died as children at a much higher rate, but there are some important caveats. In King Charles V's day, a simple cut that today we would not even think twice about could prove fatal from infection. Add to that the common plight of royal families being extremely inbred (I'm not sure if this was the case for Charles V) and it is actually likely that most people alive today, regardless of wealth, would likely live longer than him.

Now, when you compare a low wealth person today to a peasant from the medieval era, if you remove child mortality, they likely had a similar life expectancy, although again, the modern human is more likely to have access to antibiotics, regardless of wealth--as others have mentioned, they just didn't exist back then.