Set in a mythical time in precolonial America, when a race of demons begin killing humans in their sleep and replacing them with duplicates, a naive hunter must work with his tribal enemies to stop the monsters before they are taken next.

You should make it personal (I find myself saying this a lot)

"When his sister is killed and replaced by body-snatching demons, a native American hunter must..."

Instead of killing? 'humans' the demons should do something to a specific person who the lead character cares about.

The clauses prior to "...a naive hunter..." can be cut as they use none specific statements to describe backstory and setting instead of plot.

What specific event, or which particular murder, motivated the hunter to take action against the demons? If it where his brother, lover or mother the personal nature of the motivation is clear, otherwise, why doesn't he just run away to a safer place?

Point is, the story needs to be described with specific events instead of general statements, and it's best to make these events relate to the MC on a personal level.

Last point, what exactly must he do to stop the danger? Must he kill the demons? Banish them? Entrap them? Whatever he needs to do must be described in the logline for the plot to be clear.

A basic challenge with fantasy and SciFi stories is that they take place in imaginary worlds with special rules and extraordinary beings and events that have to be defined and explained before anyone can comprehend what is going on.

Alas, this logline is overloaded with "WTF?" elements that have to be? explained before it's possible to understand what the story is about.? Like:

>>mythical time
"Mythical"?

>>in precolonial America
Where? in North America, Central America, South America

>>race of demons
Where did they come from?

>>killing humans in their sleep and replacing them with duplicates
What triggered them to start doing that? What is the point, the purpose of their replacing humans?

>>to stop the monsters
How is that even remotely possible?? How will brokering an alliance with rival tribes make any difference?? Mere humans are going up against magical monsters.

A logline should raise curiosity about? how the plot ends, not questions about what the plot is about.

fwiw