Has everything already happened?

It has been said that time is not only subjective but that it is also a purely human concept. I can believe that at the moment of Creation, the Big Bang, the singularity, etc., “everything happened” and time is just a means for us to experience reality in a linear fashion.

Is this possible? Are instances of precognition and deja vu simply out of sync signals that are picked up by folks with a genetic sensitivity to such anomalies? Are dreams the by-product of a brain that had to instantaneously decipher creation?