[CuriouslyC]

Note here that you're using the word random, when in science the phenomena are unpredictable.

"You" as a stable, persistent entity does not exist, but you as a momentary observer, with the ability to exert will to guide the evolution of the universe sure seems to.

Which hypothesis fits Occam's Razor better: that the same pattern of observation and response occurs at all scales in the universe, with the only variable being the complexity, or that there are two different processes, one of which takes over only at one very specific scale? If we don't have free will, if we're just dumb machines, why would we even be conscious in the first place? IMO it's far too big a thing to just be a random side effect.

[Emma_Goldman]

What do you mean it's 'too big of a thing' to be explicable within the framework of the physical universe? That does not sound like a sensible intuition to fix on. For most of history life was thought of as too big of a thing to be explicable in terms of the physical universe, and philosophers appealed to the divine and extra-physical vitalism, but we now know that life really is susceptible to physical explanation.

As for your question as to why humans or other sentient beings would be conscious if they belonged to the physical universe, the answer is obvious: for the same reason that we and other animals possess all other attributes, because of its functional value in enhancing our survival fitness as a species. Perhaps high level information-processing requires consciousness, or consciousness is a byproduct of some or all high level information-processing with organic matter.

I should say I'm agnostic about consciousness because I think we know next to nothing about it.