Correct. A split second. I saw the deer a split second before hitting it (which you didn’t); and, we both saw the deer a split second upon hitting it. That moment went by very fast. There’s obviously no time to stop or even to try to swerve (which would be very dangerous). You just have to rely on the safety devices built into the car. Presumably, the deer dies instantly.
With respect to a human being hit in the manner of a deer, there’s got to be questions. Deer will cross (or attempt to cross) a highway with cars wizzing by at 65 mph. But not normally a human. Hence, the state police are investigating.