This is what separates the pros from the rest of us. Simply because the ball is down near our feet, most people immediately think they have to swing down at it. If you think about it, the clubhead is already down there, you didn't have to push it down there - it's also resting on the ground that's what the shaft is for.
The golf swing is the same motion as throwing a stick over your right shoulder. This is how great golfers keep the right arm bent at impact, stay in their posture, if not bending over more, and release the club naturally.
When you swing down at the ball that forces your shoulders up and your hips forward toward the ball. Basically, if you swing down you have to stand up as you do it.
When you throw the club overhanded, over your right shoulder, you have to bend and tilt and twist as you strike the ball.
If you were to do this same motion while standing upright the club would be traveling in an arc to the right of your right shoulder and the clubhead would be level with or slightly higher than your head.
BTW, If you try to do this motion with our hands in front of your pelvis it can't be done. If you watch Jamie and all great players carefully, their hands stay to the right of their body and especially their right hip until long after the ball is gone. You cannot strike a ball properly while facing it.
Although, as soon as you think "overhand," you're right shoulder stays low, the backswing is reduced and overall most body motion is reduced. We all know how to throw a club or stick. There's no thinking involved and not a lot of body twisting, at least not intentionally.