Yes, the brain takes activity from many places and makes something whole out of it
I don't think anybody is assuming the brain is only doing one thing. It is doing a lot of things at once. Consciousness only being one of them.
Mostly in terms of consciousness is the visual experience. This takes up a lot of brain activity.
But consciousness is not aware of any of this activity. It is only aware of the product of the activity. The visual experience.
So the question is: Which activity in the brain is consciousness and which is not?
On that topic we know nothing.
Thing thinking. As for one thing at a time you are doing that for your view of consciousness.
You are aware of what you are looking at. You are aware of the field eye search has accumulated. you are aware of your verticality. you are aware of the sounds on which you are focusing and the sounds from which the sounds your are focusing emanate. You are aware of all that is touching you, the wind, the heat of the sun, the water on your hand.
Yet, you are not aware that the sounds of which you are aware are out of order, the verticality of which you are aware isn't actually vertical, the visual events going on now of which you have processed of which contradicts that which you eyes are now looking upon, the false step you are about to take which you have processed but which you are unaware.
Sampling some of what has been processed and of which you have been or are aware while not being aware of other things you have processes which are important to you. All these signs suggest feelings are wave like, like one set of stone causes ripples are preferred over others because of whim. I'm saying consciousness is like that. You are feeling consistently along a single line in the theater about and within you and you are calling it consciousness. It's not that consciousness is unaware of all this.
Both scenarios are present, that consciousness has been deceived and that consciousness follows feelings rather than observations or sense data.
Decisions were made. Sense data was misinterpreted in favor of pattern and context. A twig break is more important than is a call so it is placed first. A movement to the side is more important than the statue before you so you turn your head. These are things that demand attention and consideration necessarily placed before things of interest. They are colored with potential danger, a fear feeling rather than good, comfort, satiety feeling.
It is from feeling that consciousness arises. Consciousness does not result from the passing though a particular prefrontal structure of certain information.
Consciousness is determined. Consciousness arises as the result of feelings referenced by what one is doing which in turn is referenced by what one has decided or been enticed precious to current consciousness feelings.
Is it any wonder that vision and tale dominate consciousness. We are continuously generating narratives, plans of action, which serve as both producers and recruiters of particular brain activity reference and color. Consciousness is not a guide. It is a reflection of feeling referencing arenas of sensory context, it is a fiction created as context, reason, for doing and being.