Does someone's pet rock have consciousness? I would suggest that if one hooks it up to an e.e.g. machine, it'll show flat-line. So, just because something exists doesn't mean that consciousness is present in it.
With matter, only some forms show signs of consciousness, which suggests that it is a by-product of a certain complexity that's not found in pet rocks and the likes. Matter of fact, the vast majority of that which we find here on Earth show no indication of consciousness.
Like the pet rock, for the vast majority of the history of our universe, nothing seems to support the idea that consciousness had been formed throughout most of our history. Therefore, if it's not intrinsic to our universe, then it most likely would have evolved when certain material forms were complicated enough to interact with other forms, much like forms of energy may inter-react with other forms of energy. IOW, to me the likely key here is energy. Not that energy by itself is consciousness, but that energy that channeled in some way between forms can hypothetically become consciousness.
So, where did consciousness come from? Well, under what I propose above, it gradually may have evolved over time and became common in life forms, which could have evolved as well because of the building blocks of carbon leading into protein coming from amino acids that inter-reacted with other chemicals.
Can I prove this? Of course not. Nor do I have a clue if it's right in any way. I cite it as a "maybe"-- that's all.