No, we are not living in a quantum computer. Quantum computers are physical devices specifically designed to leverage the principles of quantum mechanics to perform certain types of computations more efficiently than classical computers. They are engineered systems that require careful control and manipulation of quantum states.
On the other hand, we, as human beings, exist in the physical world and interact with it using our classical senses and classical computers. While quantum mechanics underlies the behavior of particles and systems at the microscopic level, our everyday experiences are well-described by classical physics. Classical physics is a branch of physics that deals with the behavior of macroscopic objects and the laws of motion formulated by Isaac Newton.
While quantum phenomena and quantum computers are fascinating areas of study, our immediate reality and the world we observe and interact with are not manifestations of a quantum computer.