Ok, please explain how is it that while at any joint angle and at any point of the oscillating circle, the shaft, the pin, and the axle, are locked in an exact point of the same oscillating circle, they are not constant.

Please explain How can one side of the joint accelerate/decelerate independent of the other side of the joint while the shaft's slot never disengages from the fixed pin in the axle?

Same thing applies to dogbones