The reason we don't fall toward the Sun, despite gravity being a constant force, is because of the balance between the gravitational force and the centripetal force acting on Earth as it orbits the Sun.
Gravity is indeed a constant force, but its effect depends on the masses of the objects involved and the distance between them. The gravitational force between two objects decreases with the square of the distance between their centers. In the case of the Sun and Earth, the Sun's mass is much larger than Earth's mass, resulting in a significant gravitational force between them.
However, Earth is not stationary but is instead moving in an orbit around the Sun. The centripetal force, which is the force required to keep an object moving in a circular path, counteracts the gravitational force pulling Earth toward the Sun. This centripetal force is provided by the inertia of Earth's motion around the Sun.
The combination of the gravitational force pulling Earth toward the Sun and the centripetal force keeping Earth in its orbit creates a stable equilibrium. The gravitational force pulls Earth inward, trying to make it fall toward the Sun, while the centripetal force keeps Earth moving in a curved path. As a result, Earth remains in a stable orbit around the Sun without falling into it.
In summary, the balance between the gravitational force and the centripetal force allows Earth to maintain its orbit around the Sun without falling toward it.