The Democratic Party aims to "care for the harmed", especially those harmed by the government itself. Trump appeals to those who believe that they have been harmed by the government because the government helps those who have been harmed by previous government policies. The Trump people - working class white men, in particular - believe they were in line for the American Dream, and that Democratic "care for the harmed" policies amount to letting other people - women, people of color, gays and lesbians, the handicapped, immigrants - jump the line ahead of them for no good reason. The Trump people are right that they are losing a benefit (a privilege) they used to have. But on this point I think the Democratic Party policy is fundamentally right.
The best Democrats can do to address this real grievance is the plan to reduce the cost of college, especially community college, for the ambitious part of the white working class. I would trumpet that policy right at the Trump supporters.
The harder issue to address is about the effects of globalization. The leaders of both parties are internationalists, for good reason. The world is safer with a free-trade regimen, our national economy benefits, all consumers benefit, and many workers benefit. But not all. Here the Trump supporters have a real grievance, which cannot be easily addressed by either party. Low-skilled manufacturing jobs are not going to come back in sufficient number to re-employ them at family-supporting wages. They refuse to take farmworker jobs, which can fill that gap for people willing to do very hard work (as the immigrants show).