You were saying that the human body is built to last because it barely lasts longer than machines. But comparing the human body to a machine is fruitless; the ability to self repair and collect our own energy should allow us to last almost indefinitely, not a mere 80 years. 80 years is more like you would expect from a machine.

Those capabilities -- self repair and energy collection -- should allow many orders of magnitude greater longevity. The fact that they haven't indicates that those capabilities are not optimized for longevity. Ie., we were not 'built to last.'

We were optimized for species-longevity through reproduction, not individual longevity. The fact that we've existed as a species for hundreds of thousands of years is more like what you should expect from something that is built to last.