We differ, as we know well by now, over the ultimate source of the commandments. I do not believe we placed the words of the commandments in the mouth of God but, instead, that God inspired the words. Insofar as I can discern, both of our positions on the matter are beyond conventional proof. In fact, both assumptions might be labeled faith statements.
All faith statements, including yours I think, place us in the often uncomfortable position of dealing with competing faith claims. I see no way to eliminate the situation. What we do with it is another matter. We need not resort to violence, either to persuade others to accept our particular claims or to prevent others from embracing positions other than our own. Our personal and collective egos find this hard, but enough historical examples exist to prove it possible.
With reference to "responsiblity," I believe myself responsible to the One in Whom the commandments find their origins, to the One behind them, so to speak. In effect, the commandments are not only good for forming us into persons who worship God and build healthy community. A lifetime of putting them into practice may so condition us that we catch at least a glimpse of the living God and experience what life is like in God's presence. Even if such a thing does not occur, though, observing the commandments remains good for us and all those whom our conduct may affect.
As for "story," Tolkien's concept of sub-creator suffices. The Creator God spins the primary story, but as one created in the image of God I may take the stuff of God's story and fashion my own. I cannot create the basic stuff of life, let alone life itself, but I can arrange and rearrange the ingredients. Indeed, I am responsible for doing so. By grace, God takes my efforts and weaves them into the greater story he is writing.
All of which, believe it or not, brings me back to "You shall not steal" and the previous postings. Given my perspective, it would be stealing to pretend I create anything per se. Everything is a gift from God. I may, though, become better skilled as a sub-creator, and humble enough to take joy in the role.