I admit, I did realize that it's quite highly probably that, though a Leaf Eater wouldn't kill another dino for food, that one could well kill another dino over food.
This probably (one hopes) would never happen in the Great Valley, but, we kinda did see those two dinos duking it out at the beginning of film V over food and they may well have killed the other over food had they not become food.
I actually have a fanfic, though in its infancy, where it showed that Topps lost his wife and other kids to rampaging threehorns when Topps and them got into a dispute over food and resources. Topps was only able to save Cera alone. (Note: This is in the past. Tricia and Tria are still fine.) In my fanfic, Topps had never told Cera, in part because it would hurt his Threehorn pride agenda to tell Cera that not all Threehorns were good.
Cera had believed her mother and siblings to have died in a Sharptooth attack (Cera had gotten a concussion in the charge and didn't quite remember what had happened and also she was pretty young then and so didn't recall well.) That would explain why Cera was so biased against Chomper more than the others. She thought she had lost family to Sharpteeth.
We can assume, based on Topps behavior in film III during the drought and the two dinos fighting over food in film V that, though not likely to be shown directly in the films, that yes, Leaf Eaters probably due kill each other over food in the Mysterious Beyond.
So, in that respect, they'd be no better than Sharpteeth. In some ways, they'd actually be worse, as at least Sharpteeth eat the dead dino whereas Leaf Eaters would leave the body to rot.
(In short, in the case of Sharpteeth, the killing would be need (few Sharpteeth would risk their necks to fight Leaf Eaters unless it was necessary)) whereas, for Leaf Eaters killing Leaf Eaters, the killing could well be greed )
I don't think they ever mentioned Dino Heaven or Hell, but we can assume, based on Littlefoot's mother's spirit, that there is life after death for dinos in LBT world.
As for the villain from the first film, I keep thinking that his motives were more than food. No other villain, not even Dil and Ichy, was so persistent of the Gang of Five, and he seemed to be more of a monster, just snapping at thin air when he was unable to get them and they were way out of his range.
Also, in the book version of the story, he wanted revenge for his eye (though it wasn't Littlefoot and Cera's fault as they didn't do it on purpose) and anyway, he seemed to be near the entrance to the Great Valley and had evil intentions for the place.
He even tried to take Petrie, even though he had to know he wouldn't survive going into the water. (Yes, I think that Sharptooth had more intelligence than most of the other Sharpteeth we've seen.).
Also, I'm still upset about Littlefoot's mother's death. Send that Sharptooth below!
Also, that Plated Sharptooth from film V can join him. He was pretty nasty too, willing to attack Chomper's parents just to get at the kids and, in his last moments, tried to take Chomper with him just out of spite.
