It is interesting how opposite our views in case of LBT V are. I found Littlefoot was a little too unconcerned and thoroughly trusting about Chomper. Don't get me wrong, I'm not saying that Littlefoot should have had serious doubts about Chomper's faithfulness, but the degree of his openness was a little over the top in my opinion.
What was Chomper up to until he recognized Littlefoot and the others? I don't believe he was old enough to actually hunt and kill something of their size (though the working of his excuse (I had longneck for breakfast) suggests otherwise), but if that's so, why was he chasing them?
I find it kind of odd that LBT V on the one hand is the first ever LBT sequel to make a reference to Littlefoot's mother, but it is totally secluded from the plotline involving Chomper. I really think it would have been a good addition if there had been some kind of conflict of conscience for Littlefoot given the fate of his mother and the simple laws of nature. Cera was all along presented as the "bad one" for being cautious about Chomper, but was her extreme caution totally unsensible? Even if one did not suspect Chomper of any bad intentions he was clearly very naive about his parents who he was so certain wouldn't harm Littlefoot and the others that he led them straight to the place where they were waiting. Had Littlefoot and the others not jumped into the bushes in the very last second Chomper would have let his parents right to them. And right before Cera warns Littlefoot (who had asked Chomper if he wanted to take a bite) Chomper very much DOES look like he had misinterpreted to offer to refer to Littlefoot's leg. I suppose a depiction of a deeper inner conflict of Littlefoot in LBT V would have been regarded as too complex for LBT, but I still think that it would have improved the movie. Littlefoot's trust to Chomper in LBT V is unusual given the fate of his mother and the fact that he knew Chomper for but a few hours.
One more point I hold in favor of Ruby is the basic fact that she is one of the few female characters in LBT. Look at the characters added in the sequels, almost all of them are male. Ali, Tria and Tricia seem to be the only female characters of greater importance added throughout the sequels. There appear a few more (e.g. Elzy, Sue, Old One, possibly Dinah and / or Dana), but they are hardly characters whose significance is equal to that of many male characters in their respective movies (Hyp, Nod and Mutt; Chomper, Doc, Pterano, Mr. Thicknose, Mo, Bron, Guido etc.).