There are certainly a lot of pieces to the puzzle, and lots of opinions on what caused what, but it can't be denied we had a timespan in our history that lasted several decades where we had high marginal tax rates and relatively low income inequality. During that time, wages of everyday workers kept pace with increases in productivity and general working conditions for everyday Americans improved. My understanding is there is pretty strong agreement among economists today that decreasing taxes for the wealthy and large corporations, weakening labor protections, and general deregulation have all contributed over the past several decades to erode that progress along with a large shortfall in public investment.Kind of, but a lot was happening at the time. Recovery from the Great Depression and then WWII in a row. FDR really had only part of the puzzle right
WinklerTestimony33109TheNewDealSenateTestimony.pdf
Keynes advised that the PRIVATE SECTOR to should be the driving force to counter-react.. Only if the PRIVATE SECTOR couldn't muster a strong enough response should the govt get into it. even then, the government should spend money on large public works projects, LOWER taxes, or both. He also talked about "deliberate, sustained countercyclical spending".
The wealth inequality was already diminished by the Great Depression and WWII (men left the workforce for over 4 years). FDR only stabilized the patient so that it could recover.
Honestly, I think the public investment is the most important piece right now. I'd prefer to do it funded by finding ways to tax the wealthy, but if we can't do that I'm also perfectly happy to simply accomplish it through deficit spending as well.