If "time is just movement", then it is an emergent property of the universe (and movement, or more generally - change, would be the fundamental property). Still

If "time is just movement", then it is an emergent property of the universe (and movement, or more generally - change, would be the fundamental property). Still it wouldn't mean that time is just a construct we created, as it would be firmly rooted in the underlying fundamental property (the movement you mentioned). If on the other hand it is the opposite (and based on the way we experience universe, I'd rather think it is the opposite) - then "movement" would be the emergent property of space and time; and both space and time would be more fundamental properties. In either case I don't think "illusion" is the right word, as it implies something non-existent or unreal. And even if it is an emergent property, it would still emerge from some more fundamental properties and thus would be quite real.