Evolution is a process that builds agents capable of interacting with their environment in limited ways - specifically those ways that are beneficial for their reproduction and the maintenance of the species. If simpler (ie, subjective) degrees of truth are sufficient for humans to survive, doesn't it seem extremely unlikely that we would be given the keys to full objective truth? It can be very simply proved that even your sense data, the most direct and true-seeming aspects of our experiential reality, is subjective, rather than objective (eg, blind spots in your eyes that your brain paves over, various forms of visual and auditory illusions, phenomena like tinnitus and migraines that are responsive to feedback loops involving your attention, etc). And of course, we are as humans, subjective and biased observers of our experiential reality as well. If God himself came down on a mountain in front of 100 people, you would get 100 unique reports of how that encounter happened and what it meant.
You can come at this from a sociology of knowledge perspective - what we call "objective reality" operates more like "consensus reality" - the set of subjective truths that are widely experienced by people. In most cases, we can act as if these things are equivalent, except of course, for this type of philosophic enquiry!