The Space Shuttle was fly-by-wire. In today's fly-by-wire systems, the command law commands either the load factor and the roll rate (e.g., A320's normal law), or the surface control deflection (e.g., A320's direct law). What was the case for the Space Shuttle?
The Space Shuttle's manual stick mode is called Control Stick Steering (CSS).
It commands load factor in pitch (yaw is similar). In pitch it of course accounts for the existing load from vertical deceleration. And rate in roll. When released it holds the attitude.
A second submode is indicated airspeed hold (the stick controls speed via the speed brakes), else S/B operation is manual.