Kamala Harris was not a leftist candidate nor is the DNC a leftist party. They are both center-right, with a center-left fringe that votes Democrat largely for historical reasons. In fact, it is specifically the fact that the DNC is not leftist that renders them incapable of addressing Americans' concerns. Because the center-right is the "everything's fine" wing of the DNC, which bet that they could make leftists blink and vote Harris, and lost.