The Democratic Party should be ashamed of themselves for allowing 4 years to pass without finding a better candidate than Biden.
Well yes, I agree, but the problem is, to a large extent, the process by which the candidate is selected. The primary process gives the registered voters of that party in a small number of key states the ability to select the candidate. The earliest states in this process have undue influence, many of them small states like New Hampshire and South Carolina, and the outcome of those primaries narrow the field early on, because a poor showing in those states affects the funding that candidates can raise and so many drop out quite early on.
So for 2020 the initial field of candidates was huge, confusing and full of people who were either totally unqualified, unknowns, or too far left to have the kind of broad, national appeal that is necessary to win the presidency. And that's how we ended up with Joe Biden - nice, middle of the road, highly experienced Uncle Joe. Yes he's too old, yes he's gaffe-prone and no he's not the ideal candidate (where's Barack Obama when you need him?), but he's the candidate. I sincerely hope he wins, because although he's not ideal president material the thought of another four years of Trump is enough to make me seriously frightened.