Earlier quoted context omitted.
Well, in some aspects there has been, in others not. I'm pretty sure a Syrian or a Venezuelan, for example, who was living in way better conditions a decade ago, can very easily agree that this is so. The relative stability and prosperity aside (which itself is arguable, with a declining middle class and stagnant wages, but anyway), I'm not so sure why it's so hard for e.g. many Americans to see this, as if today is…
"Inequality" doesn't mean that even the poorer part of a society has slid backwards. Considering the situation of Afroamericans, I think you underappreciate the amount of lynchings, violence (not just by police) and structural discrimination that took place. All of that is at a record low, if still much too high. There is still a lot of work to be done, but undoubtedly their situation has improved, long term.
Unfortunately it does, in two ways. One is objective, the other can be argued, but is my opinion nonetheless.
1) Inequality has seen the "poorer part of a society" slid backwards in many objectively measured standards of living, from infant mortality to overall life expectancy, to home ownership, retirement savings, and so on. Those are in absolute (and inflation adjusted when needed) values, worse than in the past.
2) Humans are not mere animals, and their progress, self-respect, etc are not just absolute, but also relative to the overall resources available. We don't compare ourselves to cavemen era people or to 1928 people, but to what's available today. More people having less share of their society's wealth is a slide backwards, even if each has more toys than someone in 1970s or 3000 B.C. had. In other words, "median share of society's wealth per person" is also a metric to keep track of over time.
(And the more important stuff, like homes, health care, education, are increasingly priced out of reach, even relative to 1970 or 1980, so that's a slide backwards whether seen relatively or in absolute terms).