Some mechanism for negative updates seems necessary. Some mechanisms for behaving defensive and pessimistically also seem necessary. I bet there are significant alternatives to the way these are set up in humans that would still result in a functional mind. But also I'd bet that our setup is basically the easiest way to do it, and evolution will reliably do things the easy way.

It was the easiest implementable from previous tools. If an engineer designs life again, sure there are other ways, but not using tools that you DO have fails at parsimony and parsimony is a pretty strict constraint on evolution by it's nature. Not being true to ones nature would be a mistake for evolution if one insists bestowing it with imaginary agency.

Not a mistake overall, but some very significant features/instances could have been avoided. Chronic pain is not necessary. Almost all clinical mental illness is not necessary. Any pain so intense you wish you were dead is not necessary. All the above are counterproductive.

@PhilosophyBear there is mitigation in form of endogenic opiates

(epistemic status: i'm materialist and maybe a little illusionist)

I haven't given this much thought so any visible mistakes are probably actually mistakes. But.

If instead of suffering all experience was positive and punishment was implemented by withholding reward, then humans would just evolve to think that the lack of reward is the greatest evil in the universe instead. That seems to be the optimal behavior, after all.

I do think that it's possible for two people to have the exact same behavior but have different qualia. A massive behavioral lookup table doesn't have qualia, but acts the same way. It's in the algorithm, not the behavior. So while an all-positive world would have the same behavior, it would feel different.

Of course, we can't even prove that suffering feels the same to us. Maybe what I experience as suffering, you experience as the taste of hummus. But we still don't like suffering, and if it turns out some people experience the taste of hummus, I still think we would not like it on those people. And that's the thing that counts, I think, so I would still classify it as suffering, even if it tastes like hummus.

Evolution is too simple to make mistakes the way I define it. It doesn't plan or care. Maybe you don't like that it found this method and of course there're other ways it could have found to implement the same behaviors, if this counts as a mistake then sure.