You've made some really good points here and I agree with most of it! And we're on the same page in terms of "hedonistic utilitarianism, with a moral circle that includes basically all sentient beings, across any point in time".
I guess my main motivation for wanting to see a historical study of well-being is because I feel that, to fully understand what makes humans happy, it is valuable to consider a wide range of possible human life experiences. Studying history does this: we can consider a wide range of societies, lifestyles, circumstances etc, and ask which humans were happy and which were suffering. And comparing this to standard "progress" measures such as violence and life expectancy can help us understand whether interventions to improve such measures are the best we can do. Then this can help us design and implement future strategies to improve well-being moving forward.
I agree that the "first approximation" I mentioned -- looking at generic factors that we expect to correlate with wellbeing, such as slavery or servitude, personal freedoms, violence -- would be a subset of "1. The history of various types of growth and progress...".
But I feel like a more detailed investigation of wellbeing/suffering through history lies outside of "1. The history of various types of growth and progress...". I say this because what we call "progress" does not necessarily correlate with wellbeing/suffering. And I think this *might* lead charities and movements such as EA to potentially overestimate the effects of intuitively useful interventions. I should add that this is potentially speculative and controversial! But I feel that there are important questions that haven't been fully tackled: Does growth really improve wellbeing? Does increasing life expectancy really reduce suffering, or does it make people overly sensitive to death? Were people in previous centuries -- where violence and disease were high -- as unhappy as we'd expect if we just look at these factors? Or are there more subtle factors that affect happiness?
Sometimes I feel like "progress" is about "satisfying people's stated preferences" rather than "making people happy". And what we think we want isn't always what makes us happy!
So rather than looking directly at violence, growth, death rates, etc, (which I expect has been done many times), I'd like to see a detailed study that looks at more direct indicators of wellbeing such as mental health, self-reported happiness, suicide rates -- and many more. And then a comparison between this and the usual "progress" studies. Perhaps this has also been done though and I've missed it.
Anyway I'd be very interested to hear what you think as I've not properly discussed these ideas before!
I would love to see a study on the history of wellbeing and suffering. This is perhaps more challenging as our understanding of how people suffered in the past is (arguably) poorly understood (as is our understanding of exactly how/why people suffer today!). But a first order approximation could look at generic factors that we expect to correlate with wellbeing, such as the proportion of people living in slavery or servitude; the personal freedoms people had; the levels of violence; and so on. Then a more detailed study -- which would probably require expertise beyond history -- would be to look at more direct (but harder to find historically) indicators of wellbeing such as mental health, self-reported happiness, suicide rates, etc.