Well, rather than argue semantics let's go to the overlays:
This is how swipes usually work. You don't outright copy the pose, especially when you are drawing in a different style. But here are the basic facts in evidence:
I wonder if this was done on a dolly (opaque projector), which would allow Shuster to play with the sizing. The spatial relationships on that diagram directly above might argue in favor of that.
• The characters are at an almost identical forward angle.
• The position of the legs is reversed but in very similar poses.
• Likewise with the right arms.
• Both are holding an oblong object which is at roughly the same angle.
• The orientation of the heads is essentially identical.
• The torsos meet up at the chest, but Shuster's left arm is anatomically incorrect. This would be expected if he were working from reference like that.
• The body and foremost head of the Hydra match up with rock in a way that makes coincidence unlikely.
• The tire hits at the same spot the segmented belly of the Hydra is located.
• The car is coming in at the rock at the same angle as Hercules approaching the Hydra.Here is a simpler diagram of the Hydra and the rock:
I wonder if this was done on a dolly (opaque projector), which would allow Shuster to play with the sizing. The spatial relationships on that diagram directly above might argue in favor of that.
That very clip-art looking car also argues in favor of a dolly. It's a bit too well drawn in contrast to the very awkward upper body of Superman.