A lot of what's considered to be 'diseases of aging' are happening too soon.

There's a lot to be said for Robert Lustig's argument that a major culprit is the standard American diet (SAD). His thesis is that this diet (plus susceptibility that's heritable) drives an endocrine imbalance (hyperinsulinemia) which drives eventual hyperglycemia and systemic inflammation.

I could argue that a lot of what you list, excepting cell senescence and stem cell exhaustion, are results of this - and it's not clear how important telomere length is (much like HDL)

As far as cell senescence, the real issue is senescent cells that don't seppuku the way they're supposed to but are instead driving local inflammation. Fasting seems to help with this, as well as removing misfolded proteins (proteostasis).

We're evolved for a diet quite different from the SAD, including occasional lack of food. Starvation has been a fixture up until the last couple of hundred years.

Related, not entirely off-topic: Peter Attia's interview with Gerald Schulman is super illuminating as to the cellular mechanism that causes Insulin resistance in muscle cells. I'm on my second re-listen, working through the show notes... I think you'd find it of interest.