Jackie is not seen to be reacting in those frames. JFK and Connally unmistakably are.
You are assuming that JFK's hand positions are not part of his reaction. That's not exactly beyond doubt.
Even if they did both react at the same time, why does that mean that JBC is reacting to being hit? He and Nellie said he reacted to the first shot by turning to look at JFK and shouting "Oh, no, no, no".
There is, after all, a not insignificant body of evidence that the shot pattern was 1.......2...3 with the last two quite close together, which means that there had been only one shot to that point.