I don't think it was Magic Negro. I think it was visions of breaking a "colour barrier."

John Edwards was charismatic and popular with the Democratic electorate. He even had a longer, if not better, resume. Their positions on the issues were pretty much indistinguishable. At no point was he *as* popular with the Democratic electorate, even before his scandals came to light. Jackson, Sharpton, and even Chisholm were "the black candidate." Obama wasn't. He certainly didn't run as "the black candidate." But he is black. Sharpton and Jackson ran on their civil rights/fighting for black causes records. Chisolm, IIRC, was similar in that respect, and also even more of a fringe candidate politically- she was more socialist than the mainstream of the Democratic party could stomach, and it also wasn't nearly as enamoured with the civil rights movement in her time as it became later. Obama is a mainstream (in his time) Democratic party politician who happens to be black. The Democratic electorate as a whole sees itself as pushing the Republic beyond that history you mention. It's progress, right?

As for Jimmy, I thought it was the calf muscles.

“Nobody has a legitimate reason to fear a faithful interpretation of the Constitution, and nobody has any legitimate reason to fear effective and complete protection of civil rights." - Alan Gura