Humans would frequently live beyond 70 years in preindustrial societies. If you look at ages when colonial aristocrats died in colonial America you'll see a similar trend.

What pushed life expectancy down was infant mortality, and communicable disease. Amish would have likely lived for longer than average simply because they didn’t live in cities.

There’s also the obvious problem of the methods of old statistics, did it include infant mortality and childbirth deaths?

Temperance.

Less exposure to disease.

They lead non-sedentary lives involving manual labor, keeping their bodies in good health. They also don't have frankenfood and tend to have actual food instead. I'm surprised people don't understand just how important these 2 factors are towards longevity.