The Humanoid Form provided a couple of benefits to the high-level animals, and one of them was endurance.
The human body serves as a form of limiter, ensuring that energy expenditure are kept lower than usual.
This makes it so that if a creature could do a certain activity for one hour straight in its true form before getting tired, then in its humanoid form, it would be able to do that same activity for three hours straight.
However, this trait of the human body came with a trade-off. That was the reduced strength.
A creature would only be able to keep at most one-third of his or her original strength while being in their human form.
No one knew why creatures could take on this form after reaching a certain power level, and no one understood why there was such a disadvantage and advantage that came with it.
In a drawn-out fight, the human form would be very good for a battle of attrition.
