Well, a lot of things from centuries past seem politically incorrect these days.   In some cases they really were racist or stereotypical even back in the day, but idioms do change. "Darkie" was once the "politically correct" term, or at least seen that way by many -- as were "colored folk," "Negroes," "blacks," etc., at other times.
(A bit tangential to this thread, but it seems that, as a new "politically correct" euphemism -- e.g., "feebleminded" or "retarded" -- gains popular acceptance, it becomes the new pejorative and must be replaced by yet another "more politically correct" term. )
As for colloquialisms such as "mammy," "chillun'," "sho'tnin'," etc,., I think of those as being stereotypically "poor Southern America" than specifically African-American (slave) dialect. Maybe it's just because I kind of grew up with Li'l Abner and Mammy Yokum and the Dogpatch crowd. :)

Ennyhoo,
I love this song and use it as a standard (and very popular) part of my Mother's Day repertoire. I use a kind of bluesy beat and sing it this way:

Chorus:
Mama's little baby loves shortnin', shortnin',
Mama's little baby loves shortnin' bread. (Repeat)

Two little babies lyin' in bed.
One was sick and the other 'mos dead.
Call for the doctor, doctor said,
"Feed those babies on shortnin' bread."

(Chorus)

Put on the skillet, put on the lid,
Mama's gonna make a little shortnin' bread.
That's not all mama's gonna do;
Mama's gonna make a little coffee too.

(Chorus)

Three little children lyin' in bed
Smell that good ol' shortnin' bread,
They jump up an' down, dance & sing,
One even did the the pigeon wing.

(Chorus)

Put on the skillet! Put on the lid!
Mama's gonna make a little shortnin' bread.
Thats not all mama's gonna do,
Mama's gonna fry a little bacon too!

(Chorus)


As for changing "gonna" to "going to," "shortnin'" to "shortning," etc., I find that a bit too reminiscent of Stan Freberg's classic "Elderly Man River" from the 1950s. LOL

Genie