Prior to WW2, we were middle of the road, but the road was pretty shitty worldwide. The rest of the western world may have moved left after WW2 because they lost a significant amount of men and women began to make up a significant portion of their voting bases. They also fought to overcome their prejudices that led them to WW2 with varying levels of success.
We, on the other hand, are incapable of looking inward and understanding our own flaws, much less fixing them. So we are still run by the same white male oligarchy that always ran us, but really that oligarchy is only interested in their own selfish interests. The only thing that really saves us is an extremely selfish individualism that is uniquely American. Even American white supremacists care far more about looking out for number 1 than their shitty cause. Same with evangelicals. Because of that, we will likely be saved from neo-nazism or Gilead, but we will also be unable to protect the environment, slow pandemics, or even maintain basic safety standards for anything long term. We are a failed state, but we are a failed state that is difficult to rule.
Trump is actually our perfect representative. He is overwhelmingly selfish and wants others to do his dirty work for him. All his followers are the same, but want him to do the dirty work. So you get some lone shooters, and some ragtag plots against governors from basement dwellers, but you don't get much real organization. Really, even our LEOs are rent seeking selfish individualists.