The racial composition of the music video may have been intentional to mirror the American Deep South, as you suggested; or it may have been a product of the times (in which the video was filmed). My only point is: if you're going to construct an alternate universe taking creative liberties, why not go all the way? (see the Freeform sci-fantasy alt-universe drama "Motherland").

Yes, I noticed the children stuffing the body in the barrell too. But, since we can only see the body's feet, I'm guessing it's one of two scenarios: A.) the children are gleefully picking on one of their peers who happens to be either taller or slightly older; B.) the children are "playing pretend" with a babysitter or temporary guardian who is an adult, and the adult is letting themselves consent to being stuffed in the barrell as part of their imaginary play.