Would a human have stopped in time? That would depend on the human…
Unlikely. These SDCs have reaction speeds far faster than any human driver. The biggest issue here is just simple physics; trying to stop a car that's already at speed requires a certain amount of distance, and from what I'm understanding, it's sounding like avoiding hitting the woman was literally impossible in this scenario (short of delaying the initial takeoff, which - in traffic - is a safety hazard in and of itself).