Using brain is voluntary act. Human tries to understand his environment and have control over his situation. So as compared to the animals he starts every task much better. He responds according to the situation. Animals respond quickly but without any intention. But when a human act he thinks before it. So the human is called as the most intelligent creature.
For example if we take a bundle of keys a human will try that key which will much the hole of lock. We do this by intelligence and observation. By keen observation we can learn correctly a lot of things. Animals cannot learn by observation but accidently animals learn some acts. This accidently act will be for a short time. A growing human baby learns a lot of thing from observation.
He follows the acts of his parents. He learns everything slowly and gradually. Animals cannot learn through observation. If a cat locked in a cage and another cat is left free to observe. The first cat that how he unlocks. But if that observing cat is now locked in cage he cannot unlock the cage. Through this example we came to know that animals cannot learn through observation. Animals learn through unintentional acts only. A human learns through listening, he learns through experiments, he learns through continuously observing others. Almighty God has gifted all humans a good and keen sense of observation and through this he goes on learning different things step by step.