• 肩かた — shoulder
• 肩書かたがき — job title; affiliation
• 肩幅かたはば — shoulder width
• 肩凝かたこり — stiff shoulders
• 肩車かたぐるま — shoulder ride
• 肩甲骨けんこうこつ — shoulder blade

肩 uses the body radical 月 (“flesh”) to point to a body part, combined with a shape related to a frame/door-like element. Think of the shoulder as the doorway where the arm “hangs” from the body — the joint that carries weight and allows the arm to move.