There plainly is such a thing. The only people who would question it are those who don't have it, and those who haven't noticed that they have it.
You might not notice you have it, in the same way that fish might not notice the water. Just consider that it's not automatically the case that you are aware of your own existence. Inanimate objects, and lesser lifeforms, aren't aware of their own existence, so something about you makes you different from them. If you call that thing something other than "consciousness", then that's fine, but it's just a different name for the same thing.