I interpret it as those ghosts that hadn't ever left The Overlook, wanted more additions to their unearthly family.
The film did allude to Jack being there in a past life, by the ending photograph shot. However, this might be a supernatural touch that all the people portrayed in the photograph, were collected members of The Overlook haunted cabal.
It's all a bit silly really, as supernatural and reincarnation can't objectively be explained. It can be whatever one wants it to be.
Norman! What did you put in my tea?

After further thought and careful consideration of the above post, I now agree with both Victor and Victoria on this one.
I don't know what the hell I was thinking when I tried to tackle it in my previous post.
Complete nonsense!

I gave up trying to interpret this one and decided it's just a bunch of nonsense.

Thank you Donna!

I agree with you on all points.

Grady knew damn well that Jack wasn't always the caretaker. Grady was one messed-up dude who was just trying to mess with and corrupt Jack's brain (and he succeeded at it by the way).
To me, it means that Grady has always been at the Overlook in one life or another. The same goes for Jack. It's a continuous cycle that never ends, so to Grady, Jack has always been the caretaker.
Wait a minute… Has Grady always been there or has Jack? If he's talking about himself, then why was he talking about Jack? And Grady WAS the caretaker before Jack (He even admitted it later on), so that has to be a lie.
What causes this continuous cycle? And wouldn't Jack have broke this cycle by being away from the hotel all of those years with Wendy and Danny? If you're going to make that bizarre of a claim, you need some sort of reasoning to back it up.
It also explains why Jack tells Wendy it was as though he had been there before (when she brings him breakfast), how he knew Lloyd the bartender…
Or maybe it's just because there were evil spirits in the hotel influencing him and guiding him around. And I think that line was meant to show us that he felt right at home there.
And was the bartender's name really Lloyd? Just because Jack called him that, that doesn't make it his name. Hell, I don't think that the dude even existed outside of Jack's warped mind-set, so of course Jack can call him whatever he wants, and he can pretend that he and Lloyd are old pals.
…and why he appeared in the photo at the end.
The key part of that sentence is "at the end". We only see it at the end, meaning that he was just put in that picture at the end, signifying that Jack was evil enough to earn himself a spot in the hotel's legacy, maybe even becoming one of the ghosts to help haunt the hotel from that point on.
And I don't buy into this "reincarnation" idea either. When people reincarnate, they don't look the same. I've never heard of anybody who believes in reincarnation who thinks that you come back looking the same as you did in a previous life. I know that Kubrick wanted to leave the door open for this possibility, but he obviously didn't think it all the way through.
There is no reincarnation. There are no continuous cycles. There's nothing that shows the possibility that Jack could have ever been the caretaker there before.
My interpretation is that they come to the hotel as a normal people, become corrupted by the evil forces, and then (if they're worthy enough) become ghosts after they die. It happened to Grady, and now it's happening to Jack.

There's an underlying theme about reincarnation in this film. This means that Jack Torrance existed in a previous life as either a guest or employee at the Overlook Hotel.
You've seen Guy Standeven in something because the man was in everything.

Depends on how you interpret it I guess. To me, it means that Grady has always been at the Overlook in one life or another. The same goes for Jack. It's a continuous cycle that never ends, so to Grady, Jack has always been the caretaker. It also explains why Jack tells Wendy it was as though he had been there before (when she brings him breakfast), how he knew Lloyd the bartender, and why he appeared in the photo at the end.
But again, it's up to interpretation.
You've had your whole beep life to think things over!