Biden won because Trump's antics in dealing with COVID offended midwestern soccer moms and because Biden was perceived as a palatable moderate. Biden overplayed his hand w/r/t stimulus out of the gate--middle America is already pissed that people are getting paid $300/wk in federal dollars not to work and, therefore, choosing not to--and inflation is a real concern, both of which Dems can be saddled with because the stimulus was rammed through without Pub input when we were on the verge of recovery without it.
I also think Biden’s overt race-based discrimination (SBA grants, farmer loans, etc.) is not going to sit well with middle America, particularly when it is struck down by the SCOTUS and enters the public consciousness, and, while middle America is still reckoning with the Great Awokening, midwestern soccer moms are going to draw the line at some of the more radical ideas being foisted upon them and their children, like having White skin makes someone guilty, the American revolution was fought to preserve slavery, and the concept of “work ethic” is nothing more than a stratagem to keep Black people down.