It is true that gravity is a very week force. But it does becomes important when there is a large mass.
The gravity between atoms is insignificant because the mass is so mall. Between atoms electricity is a greater force, the source of chemical reactions. And at the subatomic level, gravity again is very insignificant because the mass is so small. Between subatomic particles, nuclear forces are extremely powerful, but they operate over very short distances.
But when there is a large mass like the sun, then gravity becomes a significant force in the surrounding space. And the gravitational force operates over very large distances. Over those large distances, electrical and nuclear forces are insignificant.
Gravity is only meaningful in closely confined systems like our own solar system or like one of us walking around on the surface of a planet. There isn’t any way gravity could hold two stars like our sun and AC together from 4 light years distance.