If the quantum laws did simply ceased to apply at some scale, then those laws would be bizarre and unique; the first of their kind. So here comes the point: if the quantum laws really do apply at all scales, then we should expect that exactly like everything else, people (no big deal) should ultimately follow quantum laws and exhibit quantum behavior. A better question is “What do the quantum laws say that we should experience?“. The rules we use to describe how pairs of isolated systems interact also do an excellent job describing the way isolated quantum systems interact with the outside environment. When you assume that literally everything is a quantum system capable of being in superpositions of states the quantum laws become ontologically parsimonious (easy to write down).