Why is the brain a really important organ?
We can think of our brain as the control center of our body. The brain controls the actions of our body, everything that we do and think. Think of anything (including thinking) and it is controlled by the brain. Movement, balance, posture, control of senses (including, smell, touch, vision, hearing, etc.), emotions, judgement, speech, reasoning, etc., all are controlled and facilitated by our brain. The motor and sensory functioning of right side of our body is controlled by the left side of our brain, which is responsible for scientific functions (such as reasoning, logic, quantitative skills, etc.). The left side of our body is controlled by right side of brain, which also controls the our creative side (including, music, art, insight, etc.). This is the reason that head injury, which may result in damage to part of the brain, may actually cause loss of some functions of our body.
Hope this helps.