Yeah... Cannibal Holocaust was just an example I gave of the kind of grotesque movies I watched as a kid, which Indiana Jones is kind of "light" compared to even with its explicit scenes. But yes, they are two different films in themselves since HC is one of the first known found footage of the horror and gore genre (of the strongest of its kind that I consider currently exist), while the Indiana saga is adventure and action, mostly.
It is now true that this type of film is not good to show to children, and even less so to those of this crystal generation. But before, in our time, that didn't matter.
Horror and gore... that's a different trip. I was a teenager when I realized the unexpected quality of "ketchup splatters" as my friends and I ended up calling them. By then it wasn't about what got us scarred (nothing, of course!) but about how poorly the film was made, while getting away with it. "So bad it's actually good" was what we were looking for. - As for an actual scary scene, it is without doubt in Aliens (the second movie) when they are examining the specimen safely stored behind glass... which then makes a sudden move.