Nice. I agree with your conclusion but not with your premise. Our position in the world has not been granted by god. Our moral imperative has not been handed down to us. I believe we have acquired it by virtue of our nature, which is to become rational and conscious of what we do. That has been our evolutionary path. But it is not complete (if it was granted by god, why is it so undeveloped?). We tread a very fine line between consciousness and blind evolutionary advantages (opposing thumb, upright gait, and tool making ability). We really are not very much different from humans only 10,000 years ago; it's just that our tools are much more spectacular now. We still don't have much sense for how to use our tools without screwing everything up.

As for our relationship with other species........ I think the very best thing we can do is to simply leave them alone. We need to focus on our relationship with the planet, and if we do a good job with that, the other species will fare much better than they do now.