The megaverse of universes would likely require some origin, too, so positing a continuum of universe pushes the problem back a step. Does the norms of the continuum create itself or are they timeless? Is there a mega-time in which the continuum pops out universes?

I've addressed that point about naturalness elsewhere. The thing is that "natural" has many definitions, so it's possible that artifacts are natural in one sense and unnatural in another. I'm focusing on the sense in which nature is wild, as in undomesticated. In that case, the wilderness is antithetical to artificiality, civilization, culture, and personhood (the civilizing force). Metaphysically, everything may be natural, according to philosophical naturalism, but morally and aesthetically, most of the cosmos is wild, which makes our refuges anomalous. This is my reconstruction of the Cartesian dualism that's presupposed by secular humanism.

I agree, though, that there are glimmers of unnaturalness in that sense in the affairs of other species. Life in general is anomalous in the wilderness. Our species is just an extreme form of that prior anomaly.