As an academically-trained – and lifelong avocational – medievalist, I can say there is a lot of truth to this! True, there were plenty of issues in that era that could be lethal, from plague to war. But now it’s cancer, degenerative heart disease, and (in many parts of the world) still war… 🙄
In fact, most of the things that killed people – and that account for the “lower life expectancy” (which is an average) of medieval people during that age – were most threatening to children. If you once attained adulthood, you had a pretty fair chance of living just about as long as we do now!
(To be fair, one exception to this was childbirth, which remained very dangerous to women right up until fairly recent times. Young women are more likely to be resilient and avoid or survive potential issues with childbirth, which is one reason why women married and bore children much earlier, on average, than they do today.)