The actual world vs. other possible worlds I'm not opposed to suggestions. Out of curiosity, suppose someone asked you why an initial (or origin, as you put it), contingent state of affairs obtained instead of another state of affairs that could've obtained. Maybe you could use the state of affairs of God choosing to create X. Presumably that state of affairs obtained contingently (I.e., God choosing not to create X could've obtained, or whatever). What would you say settled the matter? When I say chance settled the matter, I'm pretty much saying that the matter got settled but it's not as if there is something that made it settle one way or another, it just did settle one way over the other. I'm at a loss for what else I could say other than chance.
Maybe you'd suggest that I need not mention chance because everything I associate with chance is perfectly accounted for by my having already said it obtained contingently, but that's where I distinguish that a contingent outcome could be immediately settled by something we could point to, yet ultimately settled by chance. To further illustrate, take God's choice to create:
Someone might point to God choosing to create the universe as the reason why the universe exists. In other words, God choosing to create the earth settled the matter of whether or not the earth was created. So, even though the earth being created obtained contingently, it wasn't by chance in the immediate sense, but in virtue of being contingent, it will have been by chance in the ultimate sense. So I think my mentioning chance is not without warrant. In fact, you and MU initially countered my claim of chance by pointing to another contingent event.
Sorry that was a bit long winded, but maybe you have a better way to articulate what I'm trying to convey.