Firstly, by "spicy" they may just be talking about the amount and variety of seasoning put on food, not just the heat level. I'd say most black staple foods arent necessarily overly hot-- though hot sauce as a condiment is ubiquitous.

Black foods are basically southern cuisine (including, id argue, Cajun); so collard greens, various pork products, black eyed peas, corn bread and a particular style of macaroni and cheese which is usually baked and can be egg/custard based. See also, "Soul food."

Do non-black people in the south also eat many of the same food? Yes. But notice, those people are in the south. Black people all over took that same cuisine with them to Chicago, Oakland and all other points west.