"Is he really a man of mystery ?"

In the sense that there has been much speculation about his motives, maybe to some extent.

"A folk hero.....or villain ? Arch-manipulator even?"

I think Jim Moray in the article had it about right. Here was a man with a passion that could appear blinkered. But blinkers keep the horse in a straight line, and in Sharp's case a narrow focus brought priceless results. Sharps' ideas about presenting the material haven't stood the test of time, but his material has. He may have been manipulative on a personal level, but I don't think he was an evil megalomaniac by any means.

"Did he really largely ignore contributions from black singers when he travelled around the Appalacians?"

Yes he did. Mostly because he was on a hunt for 'English' songs and didn't believe that black singers would supply him with any - a misconception, as Sharp himself must have begun to realise when he heard Aunt Maria Tomes sing 'Barbara Allen'.

"Does the "Godfather of Folk" label have much validity ?"

Only as a soundbite.