Why can a 22 C room feel comfortable even though it is far cooler than 37 C body temperature?

Answer: It leaves a heat-loss gap

It matches core temperature — This is the tempting intuition, but it points the wrong way. If the air matched core body temperature, a resting person would struggle to lose the heat that metabolism keeps making. Comfort is not about matching 37 C; it is about letting heat leave at about the same rate it is produced. A bathtub near skin temperature can feel warm for the same reason a room at core temperature would be stifling.

It leaves a heat-loss gap ✓ — Correct. A resting body is still producing heat, so the skin needs surroundings that are cooler than itself to send heat away by radiation and convection. Comfortable mean skin temperature is often around 33-34 C, while a lightly clothed room near 22 C leaves a useful gradient after clothing insulation is included. The surprise is that 22 C feels good partly because it is not close to body temperature.

It keeps skin at 37 C — Skin is not supposed to sit at core temperature. Comfortable mean skin temperature is usually several degrees cooler than 37 C, because skin is the radiator that lets internal heat leave. If the room merely tried to keep skin at core temperature, heat loss would be too weak. The more useful target is controlled outward heat flow, not making every body layer the same temperature.