It seems to me that the simplest way to summarise the heart of political polarisation in America is that:
a. Republicans, especially Trump supporters, think the Democrats are evil;
b. Democrats think Republicans, especially your "average" MAGA members, are dumb.
And being "dumb" at some level explains why Republicans are more susceptible to conspiracy belief. It is pretty obvious that the rush of Democrat conspiracies on Twitter yesterday that the assassination looked staged (no doubt based in large part on Trump instantly turning it into political theatre) will not last - especially given that one unfortunate guy was killed. By comparison, MAGA Republican conspiracies last forever.
Now, of course, any over-simplification is not perfect, but I think the "dumb" vs "evil" is broadly accurate, and explains why Republican rhetoric is so much more dangerous to the unity of America: you respond to "dumb" by education and better information; but "pure evil" is readily seen as deserving of violence and death.
That they are "dumb" also means that it is so easy for them to completely ignore the implicit "authorisation for violence" that is obvious to the rest of the world when your political leadership goes on for years about a fantasy "deep state" that wants to "destroy" you, the mainstream media being "the enemy of the people", conspiracies about elections having been rigged so as to prevent your rightful winner taking power, and illegal immigrants being cast as a group chock-full of murderous and violent intent against the "good" people who happen to have been born in America.
And the ease with which they are manipulated means they are so easily "self-gaslite", inverting the entirely reasonable warnings of Democrats and centrists (that the side that seeks revenge for their conspiracy beliefs by way of everything from show trials, mass public service sackings, rounding up of millions of people into internment camps, etc etc is the side that is a danger to democracy) into "Democrat rhetoric is leading to assassination attempts - it must stop."
So "dumb" - and so obvious that history is going to record them as mad and easily manipulated - but they can't see it because of the information bubble they live in and the bad faith motivation of the rich and cynical who sustain it.
Update: examples from just now to support this post...