After a lot of thorough research conducted by both the B.net & Reddit community, we cant be 100% certain, but can confidently speculate that Dr. Shim was a Vex overmind living in a human host within a simulation. Long story short, we are all inside a vex simulation, despite perceiving that we are in the future/present, are actually in the synthetic past (traversing the fabric of time at a rate of x1000 that what we actually perceive) and serve for observational purposes to whether our Destiny is fixed of whether Shim's changes could alter future outcomes for the Human species.