I think you make some unbased assumptions there tuppence.
You say that no animal ever asked why. I wonder how you know that since our abilities to communicate with animals are quite limited. I think you meant to say that you never heard an animal ask why.
You say that intellectual curiosity is unique to human beings. Again I wonder how you got this information.
You are just making some assumptions, they are probably correct though, but they are nothing more then assumptions. But then you start basing conclusions on some assumptions without having any evidence for those.
That is your problem I think.