That was the greatest generation. It grew out of Marxist talking points.
Regarding the Great Depression, though, the generally accepted cause are generally seen as monetary policy failures and/or the effects of deflation [1]. Of course Marxists see the cause being inequality, but this is looking for nails for your hammer: Marxists only have one note in their song. You'd think that if inequality played a large part in causing the Great Depression, that there would be a fair number of economists--whose job it is to figure out why the economy does what it does--who would agree with that view. But they don't.
Calling the Greatest Generation as growing out of Marxists talking points is just ... well, I guess if you think that socialists, communists, unionists, collectivists, New Deal people are heroes, you might think it was a great generation, but I've never heard the term "Greatest Generation" as referring to anything of the sort.
Religion went away decades upon decades ago. It went away in my parents' generation. That is not new.
In my lifetime, the main variable that has been changing the most for the negative, rapidly getting severely and dramatically worse is the cost of living and in particular the cost of housing.
Maybe the causes of everything getting worse are just that simple.
https://www.worksinprogress.co/issue/the-housing-theory-of-e...
At any rate, blaming the problems on inequality seems a lot like seeing everything as nail when all you have is a hammer. I'm not sure why OP's complaint that people don't care as much, or that they are loud and inconsiderate, necessarily has anything to do with inequality. The might feel like there's no chance to get ahead so I'm just going to not care and act inconsiderate. Or they might just be selfish, perhaps because we have ads constantly telling people "get the X you deserve". Or they might be selfish because that's human nature and since society rarely goes to church any more (only 31% attend weekly, 42% at least once a month [1]) they don't hear anything telling them that selfishness is "wrong". I'm sure you can think of other reasons that have nothing to do with economics or oppression.
Furthermore, I'm not sure that inequality produces not caring or inconsideration. Take the 1920s, which had higher levels of inequality than now [2]. People born in that decade are part of the "Greatest Generation", known for their self-sacrifice, not selfishness. My impression is that civic mindedness was actually a thing back then. And it's hard to tell what is representative looking back 100 years, but the buildings from that era seem to be well-built, and you see pictures of working class people in suits (I've seen one with men lounging around a seawall in suits, which you'd never see today). So I dispute that inequality necessarily produces what the OP complains about. (I also think the OP is also not seeing the unpleasant parts of the recent past.)
[1] https://www.statista.com/statistics/245491/church-attendance...
[2] https://www.researchgate.net/figure/Historical-economic-ineq...