Yeah, nobody likes the old THAC0 system, but that's all I know. I was just reading off the tables in the old Dungeon Master's Screen, Fighter THAC0 = 20 at level 1, hoping that the basic probabilities would be similar in 5E. But even 55% is nowhere near 95%. I think it is still safe to say that 1st level characters should not hit very often, so if I ever see a 95% chance on my screen feedback in Chapter 1, I would not be inclined to believe it. Once again, the Mists of Leira shroud us with unknowing.