Revealing mistake: In the first scene, when Nicholson is driving to the Overlook, the shadow of a helicopter can be seen at the bottom right. This is only visible in the un-matted VHS print and fullscreen DVD. (00:01:05)
Revealing mistake: Wendy has a baseball bat in her hand and Jack is trying to get the baseball bat. When Wendy hits him over the head, the baseball bat bends.
Revealing mistake: In the shot just before when Jack finishes axing the bathroom door, one of the broken pieces of wood is resting against the camera.
Answer: Effectively, Danny's shining is what brings the hotel to life. Because he has such an incredibly powerful shine about him, all these weird ghost things in the hotel are able to materialize and reveal themselves. These weird ghost things are always present to some degree, and those people with a small degree of shine get glimpses of them - like Dick Hallorann. (It's not quite made clear in the movie, but Dick saw the woman in room 237 in the book). However, Danny's shine is so great that he gives these forces enough life to appear to those without any shine, people like his father and mother. As it's the hotel that's slowly driving Jack crazy, and the hotel gets its power from Danny's shining, then I'd say there's definitely a connection between Jack's insanity and Danny's abilities. In the movie, it's not as clear as it is in the book, but Jack is effectively possessed by the hotel. He's not a flawed drunk with an anger problem who loses his mind because of isolation. He's a flawed drunk with an anger problem who's doing the best he can, until the forces of the hotel get inside his head and make him lose it.
If Danny's shining is what brings the hotel back to life, does this mean that all the previous "Jacks" had a son or daughter with the shining too?