Jan. 13th, 2016
Just watched episode 11, where the young JJ breaks a marble sink in flashback, and I suddenly thought, "Why didn't she break her hand when she did that?" Because she is shown early on in the series to be vulnerable to a normal human extent to bumps and bruises and stuff, despite having superstrength, and indeed spends a lot of the series carrying around visible bumps and scrapes.
But if you hit a big, hard, stone object with a bit of meat and bone, the meat and bone will break before the stone, no matter how hard you hit it. Not to mention that super-jumping, or whatever Jessica does, should mean broken bones, and no amount of flexing your legs and rolling with it is going to change that for any jump above, oh, I guess, twenty feet or so?
So, besides the obvious — that the scriptwriters don't know how physics works — my theory is that Jessica does have invulnerability, but only when she's exerting herself. So what she really needs to do now is figure out how to turn it on without actually hitting or jumping over something.
(Needless to say, this is a NO SPOILER zone for episodes 12 & 13, for at least a week. Because I generally don't binge-watch.)