Something to take into account was the fact that the movie had a
black lead. In
1968, this was ground breaking. Imagine! A black lead with white actors supporting
him.
The other thing to note is how the roving band of police and citizens hunting down the zombies look a lot like rednecks in the south going out to lynch somebody. I have met and interviewed Romero, but sadly I forgot to ask him if this parallel was intentional.
Also, when asked who/what the "living dead" are, Romero responded, "We are. We are alive but dying all the time."
A really good documentary to watch that explores the time period and how it influenced the golden age of modern horror movies in the late 60's and early 70's - which Night marks the start of - is The American Nightmare.