Actually life expectancy is going down.
"Overall US life expectancy shortened by 1.8 years from 2019 to 2020, to 77 years."
Again, you're going with averages of multiple groups, including the poverty stricken and those living in a gluttonous manner.
I have many medieval ancestors that lived to be 100, or near to, despite the average death age being half today's average.
My parents are still living, my father is in his late eighties, and my uncle's and aunts, close cousins of same generation are similar age. Nothing is guaranteed, but I anticipate making my nineties, just knowing my family history. That assumes old age comes into play before any unexpected demise.
BTW, the 112 and 106 old people I mentioned earlier are not my family, nor are they of the same race.
The recent uptick in average death age in the last few decades has more to do with the rapid drop in infant mortality. The noted recent drop in average age is presumably an increase in unexpected deaths, such as murder, vehicle deaths (cars, boats planes) and famine type deaths.