This has already been discussed with respect to disc throwing. The body throwing a disc is much more complicated, and much more prone to timing errors that get everything out of whack.
Anyways, here is the most correct analogy for the trebuchet and disc throwing...
support structure=upper arm
main pivot at top of support structure=elbow
primary swinging beam=lower arm
connection between swinging beam and rope=wrist
Think about the right pec drill, which simplifies and boils down the throwing motion to the essence of the trebuchet portion alone, leaving out all other complexities of body momentum, etc..
There are also some good lessons to be gained from this analogy. For example, if the structure is not firmly supported at the ground and pivot point, then the pivot would wobble around during the swinging of the beam, and this would take away considerably from the mechanical efficiency of the device...the same is true of stopping your elbow during the throw.
Also imagine adding a reach back, and getting inertia involved, plus the force applied by opening the elbow. This is definitely a complication, and would require a complete re-calibration of the system.
Anyways, lots to say on this topic, I was thinking about maybe doing a video to discuss it. We'll see if I get around to it soon.
Drivers: Starlite Wraith (158g), Gummy Champion Leopard (150g), 1st Run Z-Talon (150g)
Mid-Range: Star Classic Roc (146g), R-Pro Roc (157g)
Putt/Approach: Legacy Protege Clozer (158g), Glow DX Aviar (150g)