The topic of appearance of a classical objects in the quantum world is far from settled. My favorite hypothesis is that when an object is entangled with too many particles in the Universe that sort of cancels interference patterns leading to classical world. This avoids the need for multi-world or similar hypothesis.
This is (to me) a highly appealing model for what is going on, but we still don't really know how to go from this viewpoint to what we observe in experiments, which is the Born rule.