As most of politics, it's sadly less about actual plans than it is about messaging through catchy soundbites - something the Rs definitely do better. (none that they'd act on any of it) Ds have spent a whole lot of time appealing to constituencies that aren't the working class, with messaging that doesn't work for them.
But it's not just that: Ds have materially failed the working class. They can screech all the want about "the economy" having gotten better under Biden, they're talking about the stock market, which is entirely immaterial to people who can't even save. What is material to them is "non-core" inflation (aka food and gas - it really takes an economist to come up with such a stupid label), which has gone up real bad. And many still remember Obama as having betrayed them by bailing out the banks on their backs, and working hard to save all that rot as status quo.
Yes, D policy would very obviously be better (long term), but a whole lot of working class voters don't trust that to be the case.
I'm an older millennial, born 1984, recently turned 40.
My gramps was born 1909. Not only was he alive during WW2, he was of fighting age. Not only did he fight in WW2, he was actually one of the oldest guys in his unit, seeing as he was over 30 when he got drafted.
WW2 and other first half of the 20th century shit isn't anywhere as far back in time as it feels it is.