The unfortunate truth is that if you break life expectancy out by ethnicity, it tells a different story. Generally Asians, Latinos, and Whites are above while Blacks and Native Americans are below and pull down the average: https://pmc.ncbi.nlm.nih.gov/articles/PMC9256789/#S12 If you break the groups out and individually compare against countries of similiar ethnicity, the US is often ahead.
For infant mortality specifically, in the US we count every baby with a sign of life, regardless of the age. In many developed countries, they simply don't count too premature (under 22 weeks or 500 grams, iirc) and therefore don't consider them in the metrics. It makes for an apples to oranges comparison.
You're right on "preventable and treatable deaths" with heart disease and diabetes being the biggest contributors. The question for that comes down to "is that a result of systemic issues or individual choices?" because we can do lots about one of those.
For infant mortality specifically, in the US we count every baby with a sign of life, regardless of the age. In many developed countries, they simply don't count too premature (under 22 weeks or 500 grams, iirc) and therefore don't consider them in the metrics. It makes for an apples to oranges comparison.
You're right on "preventable and treatable deaths" with heart disease and diabetes being the biggest contributors. The question for that comes down to "is that a result of systemic issues or individual choices?" because we can do lots about one of those.