Try to keep the hand closed, and then try to pick up toys from the floor, or eat yogurt with a spoon. Fingers distinguish humans and other primates from most other animals, because they allow objects sticking. You can also try to pick up objects with toes – it is possible, but not very easy. The fingers have made it possible to use different tools.
Tools are an important stage in human development. Weapons let people to be able to hunt for food for others than himself. Some people may have to stay at home, and some have gone hunting. Later, the tools have made it possible to cut down trees, to cultivate the land, build houses, etc.
The most important finger is the thumb. The thumb moves against other fingers allowing fine mechanical thumb-index finger grip. Compared with the technological superiority of man is to relate to the brain and this grip. It is very rare in the animal kingdom: possum, koala and some primates are able to slightly similar.
You can try out the necessity of the thumb, say put, a glove in your hand so that your thumb is not in its separate compartment. Try then pick up objects in your hand.