Much of what you say here seems to me clear cut and even obvious, now that we can look back with hindsight. But I suspect you understate the nature of the problem. At least, I try to get to the bottom of why the Republicans and Democrats behave as they do.
You say the Republican party "stands opposed to inclusiveness." Isn't that an understatement in light of the tribal divisiveness of the Trump party that led to the insurrection?
You say they "almost delight in their total joylessness and harm to others." There's a term for that, though: subcriminal psychopathy. Trump's malignant narcissism goes a long way to explaining his dark charisma, since we've seen this kind of demagoguery and cult mentality before.
We've also seen the Democrats fail to stand up heroically to the monstrousness of their opposition; instead, they compromise and move to the neoliberal center. I try to explain this dynamic by looking at the difference between a hyperfeminine and a hypermasculine ethos.