Car won’t start. We checked the battery & It’s fine. Could it be the starter?

Who checked the battery and how? Have you verified the vehicle is securely in "Park" position, and the brake pedal is depressed -- causing the brake lights to come on? Have someone check that too while your foot is on the brake. Sure, it could be a failed starter, but that's tough to guess without evidence. Ideally, a starter draw test should be performed.

Try jump starting - regardless of assumed battery condition.