Wonderful review! My only point of contention lies in your interpretation of Frigga's line to Thor, “Everyone fails at who they are supposed to be. The measure of a person, a hero, is how they succeed at being who they are.”

I didn't see this as nihilism, or an excuse to not improve. I saw this doing for Thor exactly what the Gospel does for us: allows us not to despair and lose hope in the face of our many failures. The Gospel tells us not to give up but to keep trying, because we cannot possibly be "who we are supposed to be," and the times we falter are as much a part of who we actually are as the times we succeed.

She isn't saying to Thor that he can give up and stop trying to be heroic. She's saying that he IS heroic, even when he makes mistakes and fails. Much like we are perfected in Christ whether we succeed at living well or not.

This is not saying "people must simply accept themselves without trying to improve" any more than Paul in Romans 5 is telling us to sin more (which of course, as he tells us in Romans 6, he is not).

To me, a wretched (and overweight!) sinner, Frigga's words and Thor's "worthiness" of Mjolner were beautiful, and an (albeit imperfect and legalistic) representation of grace.