The narrative split in this first hour is what makes the show so compelling:
Critics noted the "grounded" feel of the first episode, where supernatural elements are initially treated as abstract rumors creeping into an ordinary town. Nostalgia: Stranger Things Season 1 - Episode 1
The boys sneak Eleven into Mike’s basement. She is catatonic, terrified, and nonverbal—until they produce a bowl of Eggos (she devours them). They try to get her to find Will using a Dungeons & Dragons board. Frustrated, they wheel out a map of Hawkins. The narrative split in this first hour is
The "Demogorgon" piece foreshadows the actual monster. Stranger Things Season 1 - Episode 1