Dreams serve us as a function of an advanced brain. Our dreams are the brains way of doing several things to solidify our level of intelligence.

First and foremost, dreams are a way of sorting good memories that need to be stored from bad memories that need to be stored. In consequential memories are ignored into the great "Forget".

Second, and next most, dreams are the brain's way of trying to solve puzzles. (I saw my friend being chased and then eaten by a lion; I don't want that to happen to me. What can I do to escape lions?) Dreaming about possible ways to solve the Lion Problem lets us explore flying away with magical wings or, more practical, climbing a tree. The next time we see a lion, without thinking, we see a tree and climb it. Dreaming had already considered doing things this way.

Finally, dreams are the brain's way to further prioritize what memories we do have stored. (Years ago, I got a telephone and had to remember the number. But, I no longer have a phone so remembering the number slowly gets removed from long-term storage.