A reciprocal view is that all sci/tech advances which led to those saved lives has also led to urbanization (=> vastly accrued need for antibiotics), automobile (=> need for seatbelts and other automotive innovations)...
We may (or may not) be "more something" (for example "more happy", "more self-accomplished"...) thanks to all those advances.
Maybe not as much as we think, as AFAIK diabetes, obesity, depression/addiction and mental illness (for example) are also hitting hard among youngsters.
I will get beat up for speaking up on this topic, but you are right and its related to food based on my researching this topic in nih.gov. First world countries are experiencing the highest mortality rates because of eating garbage. Insulin resistance being at the root of most of your mentioned down-stream problems. There are also a lot more chemicals in foods now. Pesticides, fungicides, etc. leading to auto-immune problems, allergies, chronic low-grade inflammation, higher triglycerides, higher small dense particles in the LDL cholesterol. To find some of the studies backing this, use google and put in queries like "site:nih.gov insulin resistance" and other similar terms. Some of the studies contain graphs by country. The most fascinating studies are the ones that include cultures that are still hunter-gatherers. Most of them have no traces of cardio vascular disease, mental illness, obesity and certainly no diabetes.
GIGO (Garbage In, Garbage Out) rules. Add sleep (of dubious quality) deprivation, 'bad stress' (no real motivation, extreme noise and light, near-constant state of haste...), lack of exercise... feedback-boosting the destructive process we now see nearly everywhere in full swing.
We may (or may not) be "more something" (for example "more happy", "more self-accomplished"...) thanks to all those advances.