I think we should be more kind to our ancestors. Just because they lived in fucked up times, compared to our current standards, does not mean they experienced a different quality of suffering.
Perhaps it's more about "you can get used to anything." Happiness set-point theory, etc.
If you're always experiencing some low level of pain, then the pain soon stops being distracting. It still has pain qualia, if you focus on it; but those qualia no longer impact your life. You learn to function around/through that pain. It stops having relevance to your brain's decision-making process. It stops being processed consciously.
And someone who has learned to do that, if they experience a set, larger amount of pain (a tooth being extracted, say), will experience less subjective pain relative to someone not already experiencing that low constant underlying pain, because the relative amount of pain they experienced—the pain they haven't learned to ignore, the pain that leaps to conscious attention—will be less for them, than it is for the person who normally experiences no pain at all.
Now take that concept and apply it to mental anguish or guilt/shame. I would expect that it would imply that people who lived in times where everyone had all sorts of reasons to be anguished, and thus were low-level constantly anguished—would end up less likely to get PTSD, simply because there are fewer things in their lives that can truly "pin the needle" of anguish enough to cause PTSD, when the tare on their "enough anguish to rise to conscious attention" scale has been reset higher.
Compare it to times where you had to simply endure suffering (and everybody suffered somehow), be it headache, badly healed fracture, being gang raped during some war/raid by bandits, seeing your wife/child dying during childbirth and so on. And nowhere to escape to. Apart from alcohol/natural drugs which produced many addicts - drunks were part of many societies since ever and story was often the same as today
And then you look at the historical statistics and realize that, depending on your time and place, something like 250-400 in 1000 infants died. And aside from how viscerally terrifying that thought is, it's no wonder you couldn't notice that extra 1 in 1000 until you fixed childhood plagues and nutrition. It was the terrifying scourge of the 80's, but just a drop in the bucket historically.
Say you went through a really bad breakup and your partner let you down by cheating on you with your best friend. You still love them and really want to those memories gone. You got 2 options:
1) stop listening to favorite songs, no longer visit specific restaurants or pubs, stop doing a sport you did together,
2) replace these memories by doing exactly those things with your new partner. soon you will have forgotten about them. Instead what remains is that activity/place now being your memory and not associated to another person (or the 2 of you).
What has at least a reasonable chance of working in similar situation - come to peace with whatever happened and simply move on. It doesn't matter anymore. Don't cover bad memories with new shiny ones and pretend those old ones aren't there - of course they are, till your last breath they will be.
It really doesn't matter who did what and who hurt who once things are over, it's over. Process things, expose yourself to them (at least for me it works, weird as it may sounds smoking weed and mulling things over and over makes them closed quite effectively in relatively short time - but that's my own unique mindset, no clue why it works like that). They are your emotions after all, part of you. No point trying to act differently.
How to know you really processed them? For example meeting your ex won't trigger any stupid emotional reaction. Imagine granny meeting grandpa when they are 80, would they still hold grudges? What would be the point?
I don't frequently meet up with my ex's, but have caught up with them for lunch or other things from time to time. I don't really have any sort of emotional reaction to those - the relationship is over, I've got no desire to get back together with them, etc. And it's easy for me, because I know and accept that who we are now wouldn't work out, and that's why we broke up.
But memories don't always have that same perspective. They're a crystallized point in time, and maybe that point in time is before whatever happened or changed that resulted in the relationship not working out. To me those "ghosts" can be significantly tougher to deal with than interacting with the person in present day. Making more memories in those places doesn't make me forget, but it does help redefine it as just another memory in a long list of them. It gives me options of other things to remember.
Please avoid this oversimplification of human psyche.
We are not fruit flies, we are thousands of times more complex than "replacing your bad memories"
This is apparently the backstory as to why the musician Richard D James called himself "Aphex Twin"
Prior to world war 2, getting ill from a wide range of highly deadly or incapacitating diseases (polio for example) was quite common and far more fatal then it is today.
The culture around mortality has changed a lot in my opinion.
I think pneumonia, the flu, tuberculosis and diphtheria killed more people than polio (https://www.ncdemography.org/2014/06/16/mortality-and-cause-... doesn’t even mention it)
If a child under 2 dies, you'll often see reuse of that name for the next child. There were cultural standards, particularly in Europe, around naming children after paternal and maternal grandparents and so forth (such that often you can tell what number a child was by their name if you know the relative's names).
Think about that for a second. Let's say you had a child who died at 6 months old. 1-2 years down the track you had another child and you'd use the same name.
We have totally different expectations of mortality than a century ago. A child born today in the developed world is incredibly likely to make it to adulthood. It's simply not conceivable than in an era of greater infant mortality that there weren't different attitudes to the death of a child.