The increase is mostly due to childhood mortality. I'm pretty sure 5 year olds weren't dying of lung cancer back in the day.

Life expectancy once you're middle-aged has gone up quite modestly: https://ourworldindata.org/wp-content/uploads/2013/05/Life-e.... For someone my age (late 30s), life expectancy has only gone up by about 13 years since 1850.