Earlier quoted context omitted.
By all observations it is not a riddle (i.e. there are no unexplainable phenomena) but rather an illusion.
I don't think it is justified to say that consciousness is not a riddle. There is no evidence that consciousness is more than the product of the complex physical processes happening in our brain but I don't think that makes the issue any less puzzling. How does a collection of particles completely governed by physical laws become conscious? If consciousness is just an emergent property of an incredible complex state…
I mean, it's less exciting when you break that down into the what it means for a person to be aware of themselves. For me, it breaks down to neurons & symbols, well-known scientific domains. While I may not be right, it's not difficult to come up with plausible explanations for the phenomena humans experience. Most of the mystery comes from it being very difficult for most people to even define consciousness. Much of the syntax we have for it (in the west, at least) is cobbled together from various religions, spiritualities, and extremely, extremely dense philosophers read by few and understood by fewer.
You might find Richard Hofstadter's Book "I Am A Strange Loop" illuminating if you find my explanation meager.