Issue for Dems is that they want to be the party "for the people"....but accept so much billionaire money that they're compromised.
They need more AOC, Crockett etc., firebrands, male and female. People that are attack dogs who can stay on message.
Dems also need a populist message but with progressive policy. Most Americans prefer left/liberal ideas IF they don't know which side those ideas come from. Like everyone loves ACA....but 50% hate Obamacare; not realizing it's the same damn thing.
Most of all, Democrats need a message that is soooo strong, that it can carry a candidate to victory. Think about every Democratic president going back to 1960.
JFK - sharp/charisma
LBJ - self made/sharp
Carter - self made/sharp
Clinton - self made/sharp/charisma
Obama - self made/sharp/charisma
Biden - self made/sharp
Now compare these guys to Bush 43, Evil Marmalade etc.....
Dems have won over the last 60 years with brilliant people. The GOP's playbook works with genius level politicians (Bush 41) and idiots (Trump). Dems are too reliant on singularly gifted people and need a message that can pull people to victory.