> Because, as far as we can tell [...] conciousness is dependent on our brains.
This is neither a logical/mathematical proof, nor an empirically established fact. So how do you know? Why are you making statements of faith in what seems to be the scientific worldview, when the actual scientific worldview is that we should never make statements of faith?
It's as established empirically as we can observe. Shut off oxygen to your brain for ten minutes or put a bullet through it and determine its responsiveness thereafter.
Our brains are part of this universe, and conciousness is dependent on our brains.