Yes it exists and is probably some biological product of evolution, but the brain is apparently not like a heart that pumps, or a lung that is essentially a bag that pulls oxygen out of air, it's doing something else that isn't explained using any mechanical analogy (AKA the materialist worldview).
In materialism everything we know is machines and mechanisms: From atoms to trees to buildings. It works for explaining most things, but maybe there are some things that aren't machine-like, leaving us with no way to understand it (at least not using those concepts).
Think of it like - you can program a computer to do all kinds of things, but it will never "feel pain" because that is a totally different class of phenomenon that we have no idea how to produce - no amount of code will ever make pain or joy happen to the computer - it's not a code problem. "Feeling of pain" etc. are the primitives of our experience, these little experiences add up to make up our lives and selves, but we have no idea what they are or how to produce them. We only know adjacent physical things that happen alongside it like neurons firing - which not only doesn't even begin to explain it directly but is itself a concept of the consciousness machine we're trying to explain.
In materialism everything we know is machines and mechanisms: From atoms to trees to buildings. It works for explaining most things, but maybe there are some things that aren't machine-like, leaving us with no way to understand it (at least not using those concepts).
Think of it like - you can program a computer to do all kinds of things, but it will never "feel pain" because that is a totally different class of phenomenon that we have no idea how to produce - no amount of code will ever make pain or joy happen to the computer - it's not a code problem. "Feeling of pain" etc. are the primitives of our experience, these little experiences add up to make up our lives and selves, but we have no idea what they are or how to produce them. We only know adjacent physical things that happen alongside it like neurons firing - which not only doesn't even begin to explain it directly but is itself a concept of the consciousness machine we're trying to explain.