I really don't understand why some of you think the Democratic Party's ideals are "dead" and they have to wildly change everything.
They
won the popular vote. By, like, a lot. A great deal of the reason they lost had nothing to do with policy, it had to do with
Clinton, and the conspiracy theory nonsense that's surrounded her ever since Republicans started slandering the Clintons back in the early '90s.
Just as a for-instance, all those people who felt the Democrats weren't making any effort to appeal to "middle America" or deal with the loss of manufacturing jobs? That's willful ignorance. Not only was it addressed by the Democrats, it's clearly included in the DNC's party platform;
https://www.democrats.org/party-platform
So those who voted against Clinton because of that reason, they were voting out of
ignorance, not because they were well-informed. They bought into the irrational propaganda against Clinton. They would have voted against Santa Claus if he was on the ticket, because they didn't give two shits about the facts.
Plus, as much as I'm one who wants American politics to push further left, you need to make an effort to bring in the moderates. And the moderates, in the USA, are center-right, for the most part. Pushing further left isn't likely to garner increased support. And if you're a left-winger who spitefully refused to vote because they DIDN'T push far enough left (Bernie or Bust folks, I'm looking at you), well, you have the thanks of the Trump presidency for giving them the win.