Unfortunately the extreme polarization of the US electorate has been a boon to the GOP. W Bush and Trump have been huge disasters, yet they/the GOP can count on nearly 40% of the voting populace as an automatic backstop.
In more normal less partisan times, Biden would win in a landslide vs. Trump due to the economy, the virus mishandling, the overt racism, the protests, Trump's extensive lying, Trump's extremely poor management of everything, the nepotism, the corruption, the cronies who have been indicted, the impeachment, the polarization itself, plus the boorish and crude behavior, etc.