Interesting. So your panpsychist or monistic mysticism enjoins you to deny that objectivity is possible, because that neutral mental state would be defined as being adequate to an equally mindless state of "objective" nature. In that case, the commonplace experiences of objectivity, impartiality, and neutrality would count as empirical evidence against monistic mysticism.
Now I agree that we're not as objective as modernists thought we are. I take onboard some postmodern criticism of the modern metanarrative. For example, I argue that scientific institutions are pragmatic and even Luciferian in systematically furthering our technological control of the wilderness.
But even if absolute objectivity is impossible for mammals like us, the differences in degree add up to a difference in kind. I gave you a plain example of impartiality. If we don't care about something one way or the other, we're impartial towards it.
That doesn't mean we can avoid projecting the human forms of cognition in our act of understanding or evaluation. But that impartiality is still a long way away from overflowing personal bias.
You might be running together human with personal biases. As humans, we're biased towards the humanization of the environment, but as individuals we can have lots of interests and practices, including that of impartiality/objectivity. Indeed, in an upcoming article that may interest (or trigger) you, called "Transhuman Epistemology: Knowledge in the Greater Scheme," I associate objective knowledge of X with X's humanization.