I've never really watched zombie movies or thought about what they are trying to convey beyond the brain-eating and slow stumbling. The concept of social issues within the zombie genre is very interesting to me. Being the first example of the "modern zombie era," Night of the Living Dead is an excellent example of this - especially with the way that the film incorporates commentary on what was going on in the world during the 1960s. Up until the end of the movie, it seems like just a zombie movie and I simply credited the tension to the fact that the movie was made during extreme racial tension in the U.S.
The arguments between the African American character and the white character are highly significant, but what really changed it for me, and I’m sure everyone else, was the sudden ending. There is no explanation, no reaction scenes – just the shot to the head. This ending is exactly why the film is clearly commenting on what was going on at the time it was made. The bluntness is what makes the movie more than “just a zombie flick.”