You should be putting villain on a range of hands in every situation and evaluate how your hand fairs against that range. Just because your hand is a big pair doesn't mean it's the nuts. It only matters when it's compared to villains range.

Hand 1: You didn't post any reads, so I will assume an unknown here. At FR rarely will you find me 3betting JJ, especially without reads. It's just that the majority of villains play too nitty when facing a 3bet that you won't really get too many worse hands to call when you 3bet JJ. Therefore, since you don't fold out better hands by raising, and you don't get worse hands to call all that often, it's usually smarter to just call and play a flop against his wider opening range.

Since you did make the mistake of 3betting JJ here, you have altered his range. His range is much tighter now, and your hand is likely at the bottom of his range. I would expect villain to show up with QQ the majority of the time. Anyways, I'm likely checking behind on the flop for pot control. But I wouldn't be in this spot anyways.

Hand 2: This is just played bad. Just bet/fold the flop. Yeah I know it's a minraise, but you really only have two outs if he has you beat.

Hand 3: There is no way I'm folding this flop. Sure there is an ace on the board, but you need to consider his entire range, not just the part that beats you (or that you beat). He limp/called preflop blind v blind. He can easily be doing this with 87, 67, 54, small pps, air, flush draw, straight draw, etc type hands. In my experience, a donk lead from a weak player is more often than not weak. It's usually hands they don't know how to play profitably if they were to check and you were to bet.

I call this flop and call most turn bets.