OMG, a wild William Vaughn Moody appears! (William Vaughn Moody was a friend of Josephine Preston Peabody, my 1890s poetess BFF.) Re: the death of spirit of the strong and cunning few, perhaps that depends what kind of spirit you mean? Clearly in terms of possessing any kind of spiritual core, their spirits died long, long ago.

I would assume that DuBois is using "we" to refer to educated readers - anyone who was in a social/educational position sufficiently removed to study the condition of sharecroppers rather than simply living that condition.