Not to subtract from anything you said, but something that could help us, in the aggregate, as a society, is to frame things differently.
Today, most people say "human biology is a thing of wonder" "Humans are built for longevity". And when a terrible ailment strikes, they explain it with "The meaning of life/God/The devil/We must die of something!"
In my mind, we could create a human systems biology profession where students are told during the first day at school "human biology is a mess wrought up by mindless evolution. Your job is to bring it to the exacting standards of perfection that we are able to apply to other things. In the measure we succeed, we will be able to bring dignity to billions of people."
It’s not that we can’t fix things— given enough time and resources. It is just that we need to fix too many things. Each thing fixed only makes a small difference to average uptime, and that will be true for a long time, unfortunately.
We got some big early wins from low hanging fruit of infant mortality and poor sanitation. Everything else moves the needle a lot less, and it is a really long bug list. Our environment does ongoing damage of many different kinds and we wear out.
It's actually both - a thing of wonder wrought up by tens of millions of years of mindless evolution. And most scientists would already be happy to be able to "hack" this incredibly complex system to achieve a certain goal (e.g. cure cancer), not "refactor" the whole code, as you seem to be suggesting.