Our ancestors didn't have the benefit of modern medicine, so some causes of chronic pain may have just killed them outright. On the other hand, not all of the things causing chronic pain today were an issue back then.

I was actually using pain as an analogy for suffering. I know that chronic pain simply wasn't as much of an issue back then. Which was why I compared chronic pain to chronic suffering. If chronic suffering was as rare as chronic suffering back then (they both sure seem more common now), then there is no issue.

Are the current attention-allocational conflicts us modern people experience somehow more intractable? Do our built in heuristics which usually spring into action when noticing the suffering signal fail in such vexing attention-allocational conflicts?

Why do we need to have read your post, then employed this quite conscious and difficult process of trying to figure out the attention-allocational conflict? Why didn't the suffering just do its job without us needing to apply theory to figure out its purpose and only then manage to resolve the conflict?

Fixing the problem requires removing chronic pain without blocking acute pain when it's useful.

I guess you can look at it as a type I - type II error tradeoff. But you could also simply improve your cognitive algorithms which respond to a suffering signal.