On the 13th of each month, I write about a movie whose title contains the number 13.
Wikipedia entry doesn't mention anything about Native Americans. Also, for some reason Robertson's Mr. Shroud calls the monster "Bruno," which does seem like a very New Jersey name for an evil entity. Mr. Shroud turns out to be the English priest who initially ordered the Native American man put to death, or at least I think that's what the movie's ending implies. He's definitely not quite human, and he has a supernatural bond of some kind with the Jersey Devil.
The other main plot strand involves Guillaume as a mental patient obsessed with the Jersey Devil, and the movie's confusing timeline indicates that his ravings about the creature while locked up in the world's dingiest, most poorly staffed mental institution come after the main events of the story. Most of Guillaume's dialogue is delivered in what sounds like voiceover while director Steven Stockage shoots him from a curiously distant angle, like they just got some random footage of Guillaume stumbling around his cell and then added whatever audio they needed later.