Joel Chandler Harris amply gave credit for the source of the stories he published. In his introductions to the volumes, he noted the studies of African, European, and American Indian stories made by others, and drew parallels. He did draw the tales together and invented Uncle Remus in order to present them in a form that the reading public would accept.
In his Introduction to the first volume, "Uncle Remus, His Songs and His Sayings," 1880, the first paragraph states, ".... With respect to the Folk-Lore series, my purpose has been to preserve the legends in their original simplicity, and to wed them permanently to the quaint dialect- if, indeed, it can be called a dialect- through the medium of which they have become a part of the domestic history of every Southern family; and I have endeavored to give to the whole a genuine flavor of the old plantation. "Each legend has its variants, but in every instance I have retained that particular version which seemed to me to be the most characteristic, and have given it without embellishment and without exaggeration. ..... Nevertheless, if the language of Uncle Remus fails to give vivid hints of the really poetic imagination of the Negro; if it fails to embody the quaint and homely humor which was his most prominent characteristic; if it does not suggest a certain picturesque sensitiveness- a curious exaltation of mind and temperament not to be defined by words- then I have reproduced the form of the dialect merely, and not the essence, and my attempt may be accounted a failure. At any rate, I trust I have been successful in presenting what may be, at least to a large proportion of American readers, a new and by no means unattractive phase of Negro character-...." :
He goes on to speak of the work of "Professor J. W. Powell, of the Smithsonian Institution, who is engaged in an investigation of the mythology of the North American Indians,...." and notes the appearance of similar tales among the Indians, and even notes a study of tales from Siam.
Harris was, and remains, one of the founders of American Folklore studies. An amateur, but his journalist training was ample to the task.