With Imu and Joyboy confirmed to be part of the same era, makes you question where Nika and the demon of the first world fit into this
Either we may get an even more ancient enemy down the road, or it might be explained that said enemy somehow took control of Imu's body and is acting on his behalf(the devil)
On the other hand, it makes it even more possible for Blackbeard to actually usurp the King of the world title since Imu doesn't come from this first world especially with the hint around "Davy Jones actually being the previous king of the world"