Consciousness is obviously not conserved because the human population has grown enormously without any noticable change in the amount of consciousness each individual is endowed with.
This suggests that it's not drawn from some other plane of existence.
I wasn't necessarily suggesting we're all one shared consciousness. I only said that our consciousness came from another place.
We don't even know how much matter or space there is in the whole universe. We can only estimate what's visible. So theoretically consciousness could be infinite for all intents and purposes.
And just for the sake of argument, even if it weren't infinite, but this was still the case, we may just not have reached its limit as a "resource" yet.
This suggests that it's not drawn from some other plane of existence.