The US doesn't have a political Left.
Democrats only appear left relative to Republicans, and both abandoned any sense of humility and honest concern for the working-class poor.
Both parties treat common folk as chess pieces they can move around the board while pandering to the billionaires interests, and their political and corporate proxies who refuse to protect the interests of constituents allowing corporate monopolies to raise prices, pocketing obscenely greater profits, while paying lower wages than any generation before.
Trump strategically appealed to the most base fears and motives, stoking up grievance and rage, winding people up, and tossing out the red meat, scape goats with no defence for public sacrifice.