Compared to the bird box or the movie, writer has barely tried to make story exciting or mysterious. He was so drowned in emotions of story's characters by repeating same phrases over and over as if like the whole book is copy & paste of same sentences.
And at the end he left the whole concept of creature unexplained nor at least trying to , summing it up in one page total.
If you don't have time for experimenting method of an amateur writer, I firmly recommend to read another novel.