To answer some of the questions:

"But how much of that 'movie reel' inside your head is actually a superposition of abstracted reality vs actual observed reality? All Im asking is, is it even worth it to think of a human being in terms of absolute information when their memories are so sparse from reality. We remember whats important. And the things that are important, weve remembered to remember. But ultimately, the actual holding power of the brain is quite small. The brain is a master of deep abstraction from sparsity. "

First, not everyone has a 'movie reel' type of memory [0]. ~2% of the adult human population 'just remember' and have no 'mind's eye' or 'movie' playing in their heads [1]. We also know of many savants[2] that have 'photographic' memory and can perfectly recall images and places, but many of them struggle with other tasks in life. Also, some savants can acquire their incredible abilities after brain trauma late in life. So, the answer to the questions is that it depends greatly on who you ask and when you ask them. Your brain is astoundingly strange and continues to be so at nearly every age.

"Is it like a quantum system? Where the superposition values of one subcortical system are flattened by another? So that a whole brain belief/memory is a function of the fuzzyness of each subsystem being exacted/wave function flattened by the heuristic correlation/connection between all the shitty data?"

Your brain is decidedly non-quantum. Very basically, as we understand it today, the way memory works is via synapses and the modulation of how 'strong' they are [3]. The 'stronger' a synaptic bond to a neuron, the better the transmission of 'signal' over other competing synapses to a neuron. Nature does some pretty crazy things to keep that 'idea' going, like the calyx of Held [4]. I'll repeat that, in many brain areas so far studied, but not all, your brain uses a competition system to transmit signal.

I don't really understand the next questions. What do you mean by 'flattened'?

On your points about the universe being 'flat', which I assume is different than the flattened statements you talked about, you have to remember what the brain is 'for'. Our brains eat up ~20-25% of our daily food intake [5]. That is a LOT for mega-fauna mammals. Nature has deemed that this increased usage of the food is ok though, as it helps us get more food than what we spent. Obviously, with the obesity epidemic, we are kinda past this point, but we have a big brain that helps us eat. That is one idea about why the brain is so complex, that it helps us eat more food.

Another is sexual competition. Large apes like Humans, Gorillas, and Ourangs have very complicated dominance and social structures. The reasons for this are another thesis, but it ends up helping us survive and have babies. If you have a 'theory of mind' about your troop-mates, then you can anticipate their actions and maybe be dominant and make the babies. That takes a LOT of 'processing power' and, I don't think, is a 2-D problem. Interestingly, this related highly to the eyes and knowing and guessing what a rival is doing, hence the glasses they give out to zoo patrons these days [6]. Also, dogs are the only non-primate that can do this, again a possibly co-evolution related mechanism.

Basically, your brain is 'for' 3 things. Other evo-devo scientists say it in this joking way:

You are a mammal and you encounter some thing that is novel and you have not seen before. The analysis schema is as such:
1) Can it eat me?
A: No.
2) Can I eat it?
A: No.
3) Can I have sex with it?
A: No.
4) Ignore it forever.

The brain is 'for' trying to go through that schema as fast as possible and with as high a degree of fidelity as possible. Again, jokingly.

[0]https://en.wikipedia.org/wiki/Mind_projection_fallacy

[1]http://www.bbc.co.uk/news/health-34039054

[2]https://en.wikipedia.org/wiki/Savant_syndrome

[3]https://en.wikipedia.org/wiki/Synaptic_plasticity

[4]https://en.wikipedia.org/wiki/Calyx_of_Held

[5]https://www.sharecare.com/health/calories/brain-calories-at-...

[6]https://boingboing.net/2009/04/17/gorilla-viewing-glas.html