[ithkuil]

> What tells you those records aren't in a superposition?

This! Now substitute the record taking device and record keeping substrate with a human brain and this stays true. To rephrase your question:

"What tells you the state of your brain isn't in superposition?"

A human in the loop is not the end of the story, it's just yet another interaction in the quantum system.

When we experience decoherence of a quantum system, we interpret it as if something happened to the thing we observe, yet what actually happens is that something happened to us (and in turn to every system that observes us, and so on).

This is all utterly unintuitive for us, who experience the world through those brains, who feel being there, conscious in the moment. That feeling is one of our strongest direct perceptions of the world, and yet it's affected by the mechanisms of the physical reality. It's hard to accept though; it runs counter to many deep intuitions we have about ourselves, our inner lives, our identity, our values, our belief systems.