Parts of the body closest to the trunk develop motor abilities before those further away do in a pattern of growth known as proximodistal development, which is seen in very young children. Simply put, development of broad motor abilities like arm waving comes before development of fine motor skills like legible writing.
Infants learning to control their shoulders before they have a good amount of control over their arms or individual fingers is a famous example of proximodistal development. Infants that are three months old can make fists and grasp objects that are handed to them, but they are unable to point to or even reach for objects on their own.
Reaching normally appears at six months, while the capacity to point and grasp little objects like raisins appears at one year of age.