This means that if an object is initially at rest (velocity of zero), and if no net force acts on this object, then it will remain at rest.

This means that if an object is initially at rest (velocity of zero), and if no net force acts on this object, then it will remain at rest. Consider as an example a person standing at rest on a table. The Earths gravity exerts a downward force on the person (called the persons weight) as a result of the interaction of the Earths mass with the persons mass. If Newtons First Law is indeed true, how can this person remain at rest?