It appears that the majority of the World, setting aside the question of the the truth of the notion for now, believes that this is entirely solved as the child has a soul and the pig does not?
So, for most there is no dissonance?
However, considering the progress we've already made, I have hope that we can make more.
If hunting is the only thing you can do sane ethics system would allow killing the whale no matter how intelligent creature it is. And letting members of another tribe die instead of trying to share and risking members of your own tribe to die is a sane thing too.
But things change if you a member of a civilization that can produce as much food as it wants without killing anyone.
That said, I find the idea of game-theory as a "universal basis" of ethics intriguing.