MC Daleste was an infamous figure because some of the lyrics in his songs are about killing police officers. Because of that, some people say that it was an officer that shot him, but the killer was never found.
The WAD itself is just an edgy joke that was acclaimed within the common folk. The author is unknown, but I've had friends telling me that was Marcos Abenante (Sergeant Mark IV) who made it and even the code of "Mate o MC Daleste" was used in Brutal Doom (this is certainly a hoax lmao). The creator of the WAD must've made some kind of speedmapping, because Daleste died on july 7th and on 9th of the same month there were already gameplays on YouTube.
The people in front of the stage are only there because they are doing something funny (taking a bath with soda or in a comically small basin), criminal (black people with firearms) or just because they are really ugly. There is also Regina Casé, who was once popularly known for being the "queen of the poor". And the people on the stage are only there to make a better recreation of the real life event, not necessarily because the WAD author dislikes them.
On the "architecture" side, the WAD takes place in a favela (ghetto) and there is a poster of Oakley (an american company that is very popular among brazilian people who like funk), a political poster of a guy with the surname of Fuzil (rifle, firearm), the Worker's Party symbol and the free-to-air television network TV Globo. These are all things associated with people of the favelas.
Funnily enough, this WAD made an appearance on the public television of Brazil.
Sorry about the necropost.