Or maybe it's like a first-person novel (for example, ASOIAF), where the narrator is a different person at different times. Not to freak you out more...

If I were to purely guess, my gut feeling - which of course means little with complex, unintuitive things like this - is that your inner narrator / monologue-giver really is just one single consciousness the vast majority of the time.

That is, I think there's a pretty good chance it is just "you". Phew. But I think there's also some chance it communicates in some way with other conscious entities, and it can be influenced by them as well. Different states of mind (for all meanings of the word "state") may cause those systems to temporarily "corrupt", or perhaps even substitute for, your inner narrator. For example, these could be systems that evolved well before primates, like things involved with fear, anger, sex, etc., that can partly or fully hijack the narrator, but only for limited periods of time, and usually infrequently. Maybe some guys really do, literally, occasionally think with their dick. Maybe some people guilty of "crimes of passion" really were different people during those moments. Maybe certain psychoactive drugs can put the narrator in the shotgun seat while some other stuff takes the wheel. Maybe psychotic disorders mess up the communication channels, so people start hearing those other consciousnesses "talking" when normally the neocortex would suppress or ignore most or all of that chatter.

But I think most of the time, it's just the single inner narrator. This may be the highest layer of the neocortex, which is the most recently involved system. Maybe it can tell the other consciousnesses to shut up, or speak up, or ask them to compute something in parallel, and at other times maybe it's just completely overwhelmed by them (which may lead to anxiety, delusions, and other issues).

I suspect something sort of like this is likely true, even if those other systems aren't actually conscious in any way, but are more just like cold information processing systems.

Or if not that, the next thing I'd lean towards is that there are two full consciousnesses: one in each hemisphere of the brain, with similar but not exactly the same behavior, thoughts, decisions, etc. Some philosophers have concluded this after performing studies of split-brain patients (people with their hemispheres surgically disconnected to treat epilepsy). Redundancy can be beneficial.

If true, maybe these are the two full ones, and the others are only "kinda conscious", sort of like having a few different ant brains inside your own brain. Ants are conscious, but not in a very deep way. I believe they are likely aware and sentient, but they only have a limited understanding of what's going on, why they do what they do, etc. They have their own thoughts, but they are very simple, dumb thoughts. Maybe each hemisphere controls its own respective set of one or more ant- or squirrel-like brains/consciousnesses.

Going by evolution, it wouldn't be that shocking to have one or more lower-level, cruder consciousnesses inside our brain, which the neocortex builds on top of. Maybe those are like deep learning models, and the highest executive in the neocortex is like the data scientist feeding data, tuning hyperparameters, and interpreting the output. This could maybe (partly) explain why some people with brain trauma and genetic conditions turn out to be savants - the neocortex is disrupted or routed around, and some of the raw models become more exposed and closer to the highest layer of awareness and consciousness, and they can use their billions of years of evolutionary advancement to compute and memorize things when large datasets are inputted.

Octopus intelligence is an interesting case study. It evolved totally separately, so it doesn't necessarily create a path we can follow to our own intelligence, but it does suggest possible options. And given the commonality of convergent evolution, maybe it could be giving us some applicable options.

Octopi seem to have one central consciousness, and one crude consciousness in each arm. So, 9 total. The octopus can choose to intentionally move all of its arms in synchrony, but each arm can also think and act autonomously. The arms can act autonomously even for a period of time after the octopus has died, and even if the arms are totally removed (or both). If their arms can do that, it's certainly not impossible that lobes or regions of our brain do something similar. If there were some way to safely take some regions out of a person's brain and see how those parts behave on their own (and how the person behaves without them), maybe they'd be a little like the detached octopus arms - autonomous consciousnesses, but able to be directed and controlled by a central consciousness when they're connected to one.