Black voters are more optimistic among people who aren’t career politicians. Obama and Gillum were freshmen political figures and weren’t career politicians, that is unlike Demings. That’s why Hillary and Biden didn’t create such enthusiasm.
Obama had been in elected office for a decade before running for President. Gillum had been an elected official in Tallahassee for even longer. Demings ran for office in the first time in 2012 and recorded her first win in 2016 — by any measure, she is less of a "career politician" than either Obama or Gillum.
Complete agreement here. Also, unfortunately the term "career politician" often is associated with negative stereotypes when actually a certain amount of experience in elected or appointed office is a positive attribute. Politics is one of the few professions this has become a liability. That's ain't the case elsewhere; nobody would want treatment from a doctor with no experience, nobody would take flight with a pilot that has never landed a plane.
Experience only works if one keeps up-to-date.
Politics is simply one profession where that quiet part gets read out loud. A pilot that never learned digital controls is a gone pilot, a doctor using chemotherapy as liberally as the 60's is doomed to malpractice suits, and so on and so on.