I thought I was going to have a hard time following the symbolisms, imagery, and more to understand the film but it was pretty straight forward. Sure, it was obvious at times but I think they were executed well.
First, the very beginning talks about hundreds and thousands of miles of tunnels, some that serve unknown purposes. That's our first "hint" but really, Peele is telling us right away that these tunnels are used for secret government projects, ie the clones to control people. This is somewhat supported and foreshadowed by the daughter talking about the conspiracy theory that "the government puts fluoride in our water to control our minds...oh that's right, I forgot, no one cares about the world ending
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Next, the behavior of our MC which I'll call Ade (pre Red) because I don't feel like dealing with my phone's autocorrect on that. First, Ade is watching a series of TV commercials which she barely reacts to. It could be a hint at mindless TV rotting our brains or just a testament to Ade's personality. I feel like she's an unhappy child because she's in an unhappy environment. Her parents love her but are clearly on the brink of separation. She pays close attention to their behavior and notices the lack of love between the two. I think that she may feel a bit bad for her dad who is somewhat lousy but does what he thinks is best for her. Her mother is tired of his shyt and can barely tolerate him.
According to "Red", clones (shadows) are supposed to be used to control people on the surface, but this clearly isn't always the case, nor has it been. So we're not sure if the clones were still an experiment or an actual imperfect and incomplete project. The latter could be the case because Red mentioned that the people who created copies couldn't grasp the idea of two separate souls instead of sharing one, and constantly working in the environment of shadows drove them insane, which would explain why the clones were able to leave the tunnels and do what they wanted under no authority (rabbits being out of their cages is another indicator).
Red mentioned that it was God that brought the two together, because one does not simply meet their doppelganger. It has to be a coincidence that it happens.The whole purpose, or rather, the way the world is set up is that the shadows live in a parallel life of their original, replicating their lives in a fashion either intended by the government or by the original's free will.
With that being said, shadows do not have free will, or rather they are not as free as they'd like, because they are shadows created to replicate their copies. The lightening and the escalator are two essential factors that draw both OG Ade and shadow Ade to the same location. It's a coincidence like the frisbee perfectly landing on the same sized circle or noticing the time at 11:11. Things have to line up in order to meet. Shadow Ade would have not gone up the escalator had OG Ade not decided to, and this is left a bit abstract because shadow Ade, who maliciously switched out with OG, told her husband that she didn't know why she decided to wander off, but that's when we didn't know that she was speaking about wandering off from the tunnels as a shadow. This could either be a hint that shadows are aimlessly living the life of their originals, reinforcing the theory that shadows have no free will, or shadow Ade was just omitting the truth because she's a fukking liar like that.
Next, I'd like to talk about [shadow] Ade's fear of OG. She doesn't want to go to the beach, she's clearly traumatized and the movie likes to lead us to believe it's because of her going missing as a child. In reality, Ade knows she's a ain't shyt bytch who left behind a person who had lived on the surface. She knows that when things line up perfectly, coincidences, her doppelganger is likely to show up under the same circumstances or similar circumstances from when they were little. This is why she tells her husband that she's always felt she'd come back for her. Ade knows that OG has every right to be mad. And boy is she
Ade already knows the deal from the moment the shadows arrive. This is why she tries to tell her husband to STFU when talking to the OG, Red, because Ade knows this woman is out to seek vengeance, they just don't know in what manner. Ade cuffs herself to the table because this is exactly what she did to Red.
I think it's safe to leave out explaining why Red's voice sounds the way it does and why she's the only "shadow" capable of speaking.
Moving on, Red's mannerisms are that of someone who is trying to get back control, from the way she walks, moves and remains calm while her shadow family are being mollywhopped.
The scissors are pretty straightforward, cut the ties that bind you. In this case, the clones are killing their originals because their lives had been controlled by them. Also the double symbolism mentioned in a tweet about two of the same on opposite sides created to divide or some shyt like that.
Caged rabbits represent experiments and mankind's ability and almost obsession to clone. Cloning is a capability getting closer and closer to success. In the introduction the shot focuses on the bunny in the center which begins to behave oddly the more you look at it. During Red's monolog about souls not being able to be replicated, it pans to the caged rabbit we saw in the beginning, indicating that this rabbit was a clone and it was soulless. It would make sense that rabbits are cloned as well in order to sustain food provisions for all the shadows. This is the ONLY thing they ate their entire lives.