He rambled at great length about making America great again and bringing back jobs and Kamala told folks that nothing will change. If you're struggling to understand why things went this way I'm not sure I can help.

At the very least Democrats probably should have told people they'd do something to help them instead of just assuming that people would intuit that over the long term Democrat economic policy would be more stable and provide better net growth.

People in the US are dumb as shit, you have to explain things to them and make them feel like you're paying attention. This is something Democrats have utterly failed to do reliably since Clinton 1 or Obama and it's why they lose elections. They're quite literally out of touch and don't realize it's not the 70s or 90s when blue collar workers would reliably back them because they'd (relatively recently) supported the labor movement and life was, overall, pretty good for everyone. You can't run on a policy of inclusion and civil rights for marginalized groups when the main voting group is struggling to make their own lives work.