You have to admit that this is one of the first classic American horror movies about zombies, but the plot itself does not draw the viewer to the screen too much for several reasons: first, it is a very long appearance of the revived dead, zombies appear only by the very end of the movie, and before that there are long dialogues of the movie characters and mocking of the main character over the dead, only an hour after all this zombies themselves appear and start attacking people. Secondly, there are the inconsequential actions of the heroes, who simply give themselves up to be mauled by the zombies for no reason at all. Overall, the film gives the impression not of a horror movie, but of a parody of a horror movie.
If you are interested in seeing the origins of zombie movies, I suggest you watch this particular film.