There is a definite left and right, a front and back, and an up and down. Notice that each rib is flattened, not like a pancake, but like a knife. The flat side lies on the sides of the body. Try placing the rib next to your own to see how it might fit. Ribs can be difficult to place correctly because as they bend around the body they also twist like a stick of licorice at the same time.
Some people can look at the bone and know exactly where it belongs.
Personally, I have trouble seeing the twist, but I can always feel it with my fingers. The 'hand method' for arranging ribs in correct order. The 'hand method' in action. All of the ribs from the right side of the rib cage have been placed in the correct order by using the hand method. Pick up the shortest rib, and place it between your index and middle finger.