I think you need to read the book in order to understand the movie.
Oh I did. It's one of my favorite books. I found it in a used bookstore, many many years ago, I had read it long before seeing the movie.
Keel is one of my favorite theorists of the paranormal. I also have Disneyland of the Gods, which continues some themes.
There's description and I'm paraphrasing in the Mothman Prophecies where imagine there is a building and if you are on the ground you can't see much but if go up to other levels you can see further. So for instance if you come from another higher dimension you can see further based on where you positioned.
It was something like that, anyway.
I always like the explanation because it wasn't arrogant. Mothman didn't present itself in an omniscient way and helped explain the nature of levels.
Considering I don't like scary movies because I get plagued by nightmares this was one of the better movies.
Mothman was here to help but man's disbelief and fear negated the help that was offered.
Actually now you've got me thinking about it again.
But ... you're skipping over Keel's main point, which is made much more explicit in the book. Was Mothman there to "help"? What's really great about the book is things became far more absurd in Point Pleasant than the movie makes clear during the time period right before the Silver Bridge collapse in December 1967. (Those who see the movie without reading the book may not get that it talks about events from 40 years ago ... John Keel just recently died at the age of 79.)
There wasn't just Mothman & Indrid Cold. The town also had an invasion of "MIBs" and other strange-looking beings. There also were series of UFO sightings. And "Cold" wasn't the only entity contacting Keel during this time ... there also was "Apol" and "Princess Moon Owl". (You can also read Loren Coleman's books, his opinion seems to be BTW that mothman was a garden-variety cryptid and much of the rest was Keel's active imagination.)
That's just it. He believes that Indrid Cold and the other entities he encountered could see the future. Simply by existing outside or slightly 'higher' on our space-time continuum, they can see further "into" time than we can.
However, he said they frequently lied about what would happen - although they gave him some accurate predictions, others never came true. His key point is just because their perspective is a little bit better than ours doesn't mean they are necessarily good or benevolent or have our interests at heart. Remember, as he points out, although they warned him something terrible was going to happen ... they told him it would be an explosion of a chemical plant, not the collapse of the bridge ...
Keel repeats what Swedenborg once said about the spirits: the one thing he was sure of is that they lie & manipulate. "Belief is the enemy".
Or; "Trust but verify".