https://www.youtube.com/watch?v=12-WXcIpkjY&list=PLP6HLz-gb44CzeFe1N1LdlvaV8mKXTO3b&ab_channel=Gibby
SPOILERS SPOILERS SPOILERS
I've had this theory/interpretation since the summer of 2010 when the series ended, and it's been growing ever since. I finally started on a video series and most of it is finished/posted.
It started with the question of what exactly is the Flash/-Sideways/Afterlife/Bardo in the final season? Clearly it comes from 'the Light' at the Heart of the Island. But then I noticed an interesting little detail. When Desmond is transported to the Flash-Sideways, he is placed in a giant wooden Box. Also, the Series Finale opens with a montage of conspicuous shots of the Large Box transporting Christian's body to the Church.
Why is the statue underwater in LAX? Because one of the last things Kate said to Jack was to let the island sink, and he didn't. Miles talks about ghosts only being who they were when they died. So the Flash-Sideways is the Magic Box, giving all the people touched by the Island what they still wanted at the moment of their individual deaths.
I remembered Ben's speech about the Magic Box. Whatever you wanted and imagined would be inside the Box once it was opened. Everyone's afterlife storyline is based around fulfilling and reconciling whatever was left over at the time of their individual deaths. John found out Helen died of cancer the day he died, so she is the focus of his Flash-Sideways, Hurley still misses Libby, Kate still regrets stealing Aaron, Sawyer misses being a Dharma cop with Miles, etc.
Then I remembered JJ Abrams' Ted Talk about the Mystery Box in storytelling (mostly in reference to the Hatch).
He talks about how the individual imagination places something different in the Box for everyone.
Then I thought about what the Hatch was. A container for the Electromagnetism. Not unlike when Jacob is describing the Island as a bottle of darkness with a cork. The darkness being the Smoke Monster, who came from the Light.
This is not unlike the Freudian model of the subconscious mind, the collective repressed thoughts in the mind, just beneath the surface of the self, contained by the Superego.
It never made sense the way that 'Walt' led Shannon to her death, exactly the way the MiB would. Walt wasn't dead, so could it be the MiB? Well yes, because the dead are part of the collective subconscious, and Shannon projected her repressed guilt (for losing Vincent) onto the Monster, allowing the MiB to take the form of Walt, the Horse, the Spiders, even the dreams and visions that led Locke along episode to episode. Smokey led Locke to the '?' so he would lost faith and fail to press the button, allowing the MiB to escape through the Swan pocket.
Then it all came together. The Light is the Island is the Magic Box is the Mystery Box. "It's not an island. It's a place where miracles happen."
The Light/Island created the Smoke Monster as a defense mechanism. As part of the Island, the Monster is the Magic Mystery Box too, scanning flashbacks and manifesting inner darkness to lead Candidates astray from the path to redemption laid out by Jacob.
Jacob and the Candidates subconsciously project repressed desires (dramatized as flashbacks) onto the Smoke Monster (Jacob projects the Brother he murdered just the same as anyone else). Smokey has no permanent identity. It is a part of the Island, and of the people who come to be stranded there.
The Monster slowly becomes consumed in the identities it takes. That's why as Christian, it kidnaps Claire. Christian was in Australia to see Claire before he died. Smokey becomes more and more like Locke over the course of Season 6.
Anyway, give it a watch.