deputy, subordinate, concubine
簉 centers on a secondary or accompanying role: a deputy who assists, a subordinate who follows, or a concubine who is a lesser partner. The common thread is being one step below the main figure.
簉 combines 竹 (bamboo) with 造 (make, build). The exact historical origin is uncertain, but it likely relates to a secondary or accompanying role, perhaps originally referring to a bamboo object used by an attendant.
Bamboo 竹 over 造 (make) suggests something made of bamboo that accompanies or serves a main purpose, like a deputy's staff or a secondary tool.
For シュウ, imagine a deputy named Shu who always carries a bamboo staff: Shu -> シュウ, and he is the subordinate who assists the leader.