Essential Basic Rig

IK is on each leg. Here we have our Reverse IK (Maya-style) setup.

The IK goals are linked to the big round controller around the pelvis. This controls the Center of Mass.

The base of the spine is also linked to that COM controller.

This COM controller is aligned to the base spine bone.

It is linked to the round controller on the ground, which is the master controller.

Notes
The head bone is a simple model linked to the neck.
Clavicles intersect the upper spine/chest.
Taper is set very low:

You can add movable hand controls for IK arms ... these controls are locked so they do not rotate. These hand controls can also be linked to the COM or Master ring controllers.

Note
Gradients across multiple bones are set in bone tools: