The left wing didn't aimlessly move left away from labor. Biden was dramatically more pro-labor ("New Dealy") than Obama. The right wing lost their fucking minds because we elected a black man. Trump himself is a one-man microcosm of this: loosely Dem-aligned until... Obama.
Spend some time with the GOP base. They're actually broadly racist, ranging from slightly (and ashamedly) to loudly and unabashedly. The left obviously also has various problems with race, so don't take this as some implicit categorical exoneration.
And she's a woman and she's black, again. Then there was the issue that one side of the Democratic party wanted to support Israel more strongly or something, and the other side wanted to protect gazaans and the Palestinians. I think many people wanted to do both at the same time, but there is a fair number of people that picked one side or another. Some of those people voted against her. Some people in my family thought the biggest problem facing America was dei.
I can think of a couple of things that rank higher on the 20th Century's original sin list.
Rather, Obama's election was the just the last time that the New Deal coalition was strong enough to hold together, having deteriorated over the course of the 90s and 2000s because it had no clear purpose. Capital no longer feels any need to throw scraps (like limited NLRB-disciplined union organizing, Social Security, Medicare, consumer surplus) to workers to prevent 1918 happening here, which had been the Democratic Party's entire purpose since FDR. It had seemed increasingly ludicrous that revolution would come to American over the course of midcentury, but the collapse of the Soviet Union in 1991 brought the farce to light.
In other words, we're still eating the leftovers of anticommunism, the 20th Century's original sin (to mix a metaphor).