Why do we have bones?

Have you seen a circus tent? The canvas of the tent is supported by a number of poles. If you suddenly removed the poles, the tent would collapse.

The pole support the soft, pliable canvas of the tent. They also help to give the tent its shape. The same applies to our bones too. The bones of the human skeleton support the softer parts of the body and give the body its general shape. If the skeleton of a body were suddenly removed, the body would sink to the floor in a shapeless mass.
The bones also help to protect the softer parts of the body. The skull forms a strong case for the very soft brain. Two bony sockets in front of the skull protect the eyes. The spinal column forms a bony tube that protects the delicate spinal cord. The ribs form a hard elastic framework that protects the heart and lungs. If a person had no ribs and bumped into someone, even a small bump might collapse the lungs or damage the heart.
Bones also provided anchors to which muscles are attached, and bones provide leverage for the movement of the muscles.
There are two other things that bones do for the body: the inner parts of some bones make blood cells, and bones are the body's chief storage place for calcium, a chemical element very important to the sound health of the body.