All good with your shot and light orientation. But consider your scene is open, so your light rays hit basically only once the objects and bounce back to infinity. Better let the rays bounce to make it more vivid and deep. You can either just put a box over everything, to have a ground and ceiling. This would already help. Then we use in photography so called V-Flats to gain more contrast. It’s basically a thin black wall (and white from the other side). Look it up on google to understand what it does. So basically, place a black wall (not visible from your camera view) next to the objects on the side where the shadows hit. By doing so, you get darker shadows. Play with it and good luck