(SPOILERS AHEAD)
The movie NOPE was an interesting upon seeing the trailer, however the movie was way too long to not even solve a main goal. What the alien is and where it came from. Despite seeing the whole movie I still do not understand what attracts it and what it is afraid of. The entire film did not make sense and after rewatching key parts of this film, It still does not make sense why the monkey killed people. Also why that was important to the plot and main antagonist, to me it seems like the creators wanted to combine a few horror stories into one movie. (Which to be honest they did not do well).
Possible theory; the monkey was the alien in disguise, that could explain why it killed many people. It could also explain why the alien only attacked that area and attacked the protagonist OJ. (Since he was the person who watched him die, and didn’t help him).