First, the Democratic Party failed to convince 60 + million Americans of the threat posed by the worst President in American history. Second, it is a truly sorry comment on the American voter that so many of them remain under the spell of this fascist - not even a fascist who got the trains to run on time, but a fascist who broke everything he touched.
It is a sorry commentary on the state of American politics, and a grim harbinger of evils to come.
I doubt that Biden can fix this, and perhaps no one could. A lot depends on how much Mitch McConnell is willing to damage the US for his own purposes. It is unlikely that serious reform can happen with him running the Senate, and not very probable that he will cooperate enough to stem further disaster.