If there is no higher consciousness in this universe than our own, then how is it that ours so spontaneously came into existence?It didn't. Consciousness is the product of brains. And brains are the product of billions of years of evolution. There's nothing "spontaneous" about it.
Perhaps an argument could be made that God intervened in the evolutionary process and bestowed consciousness on man?
But why would we resort to supernatural explanations at all? It's ok that there are things we still don't know. Maybe it will be solved in our lifetime; maybe not. There is a lot that is known about the brain that was mysterious just a few decades ago.
Every mystery ever solved so far has turned not to be magic.-----------------------------
With regard to the above:
It's not that I have never invoked physical and natural explanations for phenomena encountered - or have never defended them. I've done so on occasion on this forum. But I think (sic) that our thought processes and awareness of them pose problems for natural science that have never been fully resolved - and they have been lurking for at least the time that Descartes first submitted his proposition.
Descartes evidently is no longer with his, but he once existed ( Cogito, ergo sum ... ergo erat), But since he ceased and all manner of mass, energy, moment and other measures in this universe are conserved, where did he go? Where did he come from when he came into this world. Is there a supply of that essence from which he came? Is it unique to us on this earth - or do we share it with cats and dogs? Does it exist elsewhere in this cosmic domain?
Newtonian physics is description of the interaction of two or more masses, but it does NOT explain how there can be interaction at a distance. Genetics and evolution, sad to say, do not explain this either. General relativity takes Newtonian physics to the next level, but it has its rough edges too in unification....
But I am starting to digress. The device I write this reply on has many so-called intelligent features, but it is not sentient in the same manner as you or I. Passing a Turing test does not assure sentience or awareness - only that the coder of the algorithm is clever enough to fool someone in conversation on a telephone line.
You can observe this essence in many ways. Clip your nails and you are not at loss. Yes, it resides in the head and brain in some fashion - just as a CPU resides in my laptop, but there is something more to it than simply code. Roger Penrose, I suspect, in "The Emperor's New Mind" seems to suggest that we will find some exotic particle in physics to explain our phenomenon, but I doubt it.
The simplest Occam's razor style answer I can think of is that there is something about consciousness that points to more than simply our own. If eukaryotic cells are a stretch from prokaryotic, then consciousness is orders of magnitude more. Unless there was a head start somewhere.