I feel like "Jaws" in particular would have gotten an R rather than PG-13
Never seen anything like the shot of the disembodied leg in any PG-13 stuff. Yes, PG-13 films are sometimes violent but not graphic like that. And though they were less graphic, the scenes where the shark eats the little kid and Robert Shaw isn't PG-13 friendly.
I also feel like PG-13 is a bit of a stretch for "Raiders" given the face-melting stuff and the nature of some of the other violence but it's probably more plausible even if deals with more mature themes that a lot of 13 and under kids probably wouldn't grasp.