Very simply for ya what caused Trump is that Americans were pissed off with the establishment and wanted someone who they thought could shake things up. (And of course a little help from the Kremlin) Well they did get a shake up but maybe not exactly the one they were hoping for. CEO's salaries continue to rise while working stiffs remain stagnant. Of course Covid has had a big effect there. Well, they can correct the Trump problem next week, Covid will take a while longer. I wouldn't say Biden would be my first choice but his theme of being president not just for blue states or red states but for the United States is a sensible place to start.
You've missed one main point and that's that Biden isn't going to fix that which isn't Trump's fault. Biden is an establishment bid to keep the status quo in place. Those people are still afraid of a real fix that's going to take a leader something like Bernie. They see that as communism or socialism and the Dem party was still afraid to go there.
I think it's quite delightful really. China gets breathing room as they fight with themselves.
Or maybe you do understand that but just didn't spell it all out completely? I hope so because it's really quite elementary.