There is a left in the US. It’s just not very powerful (institutionally) but there is a third force in American politics that has been gradually gaining steam in the past two decades (WTO protests, Antiwar, Occupy, BLM) or so as underlying economic crises manifest into political crises, ie paralysis, polarization, etc

Bernie’s campaign was largely able to have such momentum because he gave voice to that force. Rebuilding the left is an ongoing project. Yeah, the Democrats are right wing. No shit. But that doesn’t mean there isn’t a left