It’s an origin story
The movie Annabelle: Creation is an origin story on the spin-off horror movie Annabelle that was previously mentioned in The Conjuring.
The Mullins’ child died
The Mullins’ child, Bee, died and they wanted her to be alive. Some demon wanted to take shape so it began communicating with them and making it feel as if it was Bee who wanted to come back to life.
Annabelle was Bee’s doll
Annabelle was Bee’s favorite doll. She was closely connected to it so it began moving on its own. Samuel Mullins, Bee’s father, was the doll-maker who actually made Annabelle as a special edition doll.
Annabelle was possessed by a demon
A demon possessed Annabelle known as the Ram.
The Ram attacked Esther
The Ram attacked Esther, Bee’s mom, which caused the family to lock up the doll with help from the church. Samuel made a mask for Esther to wear because half of her face was torn off.
Orphans came to share the house years later
The Mullins opened their house for orphans to stay under their roof. They did that to redeem themselves for letting a demon in.
Janice was the weakest
Janice was the weakest out of the group because of her leg. She couldn’t play with them or explore with them, but she was curious enough to go into Bee’s room where Annabelle was locked.
Janice released Annabelle
Janice released Annabelle because of The Ram’s power that made Janice go to the room and open the door. She released the demon. (See The Witch (2015) Movie Explained)
The Ram taunted Janice
The Ram taunted Janice and finally possessed her when she couldn’t resist. Only Linda saw that.
The Ram was actually inside Annabelle
The Ram was actually inside Annabelle but managed to take control over a human body, namely Janice; however, it had to keep the doll that it’s connected to close by.
It finally managed to take over Janice
The Ram managed to take over Janice completely, which led her to another orphanage where she was adopted later on.
The ending explained the beginning of Annabelle
The ending of the movie explains why Janice’s foster parents were killed as a sacrifice to The Ram. It also explains why that The Ram demon was closely connected to the doll. (See Interstellar (2014) Movie Explained)