As an observer with a different perspective to you, I see that most Americans aren't ideologues so the Obama policies and ideas just don't appeal to them anymore, 8 years was long enough for them to try them out and wait for the benefits to be experienced their own lives. For some people they saw an improvement, others not. I doubt the dems can convince the latter to support them with the same old promises that were never honoured. Then there are the awkward 2018 employment statistics - how many Americans are now thinking, why couldn't Obama do that?
Fresh ideas are definitely required and they should be more appealing than the good ones pushed by Trump if you want to stop his bad ideas from proceeding.
As the guy who started the #walkaway movement alludes to, the diversity of separate groups (identity politics) is in the process of destroying itself, which was inevitable, tribalism and conflict are intrinsic to one another. I think it would be healthy for the party to distance itself from all that.
PS Jonathan Pie was created by a left leaning British comedian.