You’re right. The original is FAR closer to the book. There are so many weird changes in the remake that define it as far more a Coen Brothers creepfest than a movie made from Charles Portises’ wonderful novel.
You’ve pointed out the one big change in the original: Campbell’s death.
I don’t recall the ending of the original. (I liked both movies). But I do recall being very gripped by the ending of the remake in Rooster’s attempt to save the girl. Running his horse to death like a madman, then running himself like a madman. It was a good juxtaposition (sp?) of him being mean and ornery and his compassion for this young girl.
And I liked the new girl as well, and IIRC she had an interesting story on her getting the part - but I forget what it is now.