Sorry to dredge up an old post but I came across this searching for something else. The start of the song from the op resonated with me also. I believe the beginning reminds me of “searching for Jessica” from The Man from Snowy River. It is the one where she wakes up stuck on the cliff.
One of the old songbooks had music written by the man who did some work for movies. You could plainly hear parts that were influenced by that in his music. But given that the WT steals pictures for their own use, it isn't surprising that music is also stolen. Most of the music is so dreary that anything that stands out as melodic, has a great likely hood of being "inspired" from other music.
And I agree that this music is heavily influenced by another piece of music. If there wasn't singing going on, it might be easier to figure out. I haven't watched a lot of movies for several years so I am behind on this.
The other thing - gray songbooks that match the music
The Presbyterians have a TON of music that both in words and music sounds a lot like Watchtower, at least the old song books (pink, brown and paperback) I remember.
At least their books put a little note on the bottom who wrote it originally or what it was adapted from.
There are plenty of free (public domain) or low cost license Christian hymnals. It wouldn't surprise me if some of their song writers looked for "inspiration" elsewhere.