By pushing the idea that the humain brain is capable of “free” decision making to adapt to its environment without being forced by external factors it seemed to me that it implied an exception, or, otherwise, you’d be forced to extend that hypothesis to all living beings, and causality would surely take offense ?

I’m answering, but I see what you mean, and I generally agree with it. I just tend to think the idea of free orientation/action is both dangerous and the reason of a lot of human suffering. I’m also a compatabilist, but I another way I suppose.