Is Reality Real?
Human reality is a nebulous concept. Anyone who has had a vivid nightmare knows what it's like to be trapped between a memory and a dream. Those experiences lend credence to the notion that the senses have limitations. Perhaps the eyes, ears, and sense of smell do not tell the whole story about what is going on around them.
Maybe the things and people in people's lives are just illusions. How can people be certain that any of these objects or creatures exist? Perhaps they are creations of their own internal mechanisms, spawned by their subconscious for unknown reasons. The universe could be a hologram, a "Matrix"-style computer creation designed to capture their minds and enslave them for a sinister purpose.
Scientists and physicists are skeptical that people will ever comprehend the nature of reality. The more people learn about physics, the stranger the universe's mechanics become. From molecules to atoms, people are constantly discovering new particles and fundamental forces that drive their bodies and the world. It's entirely possible that the universe is made up of dozens or thousands of dimensions that people will never directly experience.
It's unlikely that the scientific rabbit hole people are falling into will ever come to an end. Reality will always be an abstraction that humans can never quite pin down, no matter how intelligent people's species becomes.