User is another word for a person. But when we use that word to describe someone else, we're likely implying that they're using the thing we're making. It could be a website, a product or service, a grocery store, a museum exhibit, or anything else people interact with.
We're full of contradictions. We're known to exhibit strange behaviors. From how we use mobile phones to how we traverse grocery stores, none of us are exactly the same. We don't know why we do what we do. We don't really know why we like what we like, but we do know it when we see it. We're fickle.