> Your statement of average lifespan "improving" for individuals is simply nonsense.
It’s factually correct. For example [0]:
Life expectancy increases with age as the individual survives the higher mortality rates associated with childhood. For instance, the table above listed the life expectancy at birth among 13th-century English nobles at 30. Having survived until the age of 21, a male member of the English aristocracy in this period could expect to live:
1200–1300: to age 64
1300–1400: to age 45 (because of the bubonic plague)
1400–1500: to age 69
1500–1550: to age 71
17th-century English life expectancy was only about 35 years, largely because infant and child mortality remained high. Life expectancy was under 25 years in the early Colony of Virginia, and in seventeenth-century New England, about 40 percent died before reaching adulthood.
During the Industrial Revolution, the life expectancy of children increased dramatically. The under-5 mortality rate in London decreased from 74.5% in 1730–1749 to 31.8% in 1810–1829.
[0] https://en.wikipedia.org/wiki/Life_expectancy#Variation_over...