Why do fields point in a direction?

A field isn't just "how much force is around here". It also tells you which way the force would act.

By convention, the direction of an electric field is the direction a positive test charge would be pushed.
So:

• Around a positive charge, the field points outward.
• Around a negative charge, it points inward.

Since fields have direction, they can be combined at any point. The total field is the vector sum of the fields at that point.