I was very skeptic when I first heard that the GOF was to be expanded in the TV series to become a GOS including not just Chomper, but also another character who (according to Aria) was initially meant to be named Ovie before her name was changed to Ruby.
As in so many other respects seeing the TV series did change my mind to some degree. They did manage to adopt the new characters without this move going at the expense of the role the other characters play and Ruby is a rather interesting character instead of a mere attempt to catch interest by just throwing a new name into the ring (as has been the case in some other series).
In some ways Ruby is different from all the other characters. While she is friendly and sociable, she also has moments when she wants to be alone with her thoughts which is something we haven't seen from the other characters (Littlefoot's "On your own" trip in LBT 6 was based on a different motivation). None of the other characters ever came up with anything like a "thinking place". Perhaps Ruby is the kind of character who thinks about many things the others won't bother with at all. Sometimes there is a melancholic trait about her too, because of her separation from her family (a trait which we might rather expect from characters like Littlefoot whose mother is dead rather than just somewhere else (which is the case with Littlefoot's Dad)). I sometimes wonder what is keeping Ruby's parents and her younger siblings from coming to the Great Valley too. And I also wonder if Ruby's diet has ever been the cause of uneasy feelings in the Great Valley. The snapping shell indicates that the authors of the series did not fail to notice her being an omnivore. Perhaps her ability to settle with green stuff too makes the matter easier than Chomper's case, but still I could see why expecting parents would not feel happy to have a potential egg eater anywhere near their nests. With Ruby being a very sensitive character a story along those lines might be quite interesting. I sometimes wonder if her being more reflective than most of the others makes her a bit more withdrawn herself. While she is very ready to encourage others to share their feelings with her and the others (e.g. her reaction to Cera admitting that she was scared) I think it takes a bit encouragement on the part of the others for her to speak about this.
More than any of the others Ruby is a thinker and loves to express her thoughts (sometimes very simple facts) in a somewhat tricky kind of talking (a habit which can be found among many people who think too much).
As for her age, we can draw some conclusion from the episode "The star day celebration". With all the star days shown in that episode we see that she is at least 6 years old, but possibly older. Being asked to take care of Chomper strongly suggests that she is older than him (very likely considering Chomper was born after the whole rest of the gang too) but I don't think she is necessarily the oldest. She may be, but I don't think any age difference between her and Littlefoot is very substantial. One might think that her greater knowledge might suggest her being older than the others, but in any case I hardly think that the claim that she is old enough to enjoy the "wisdom of ripe old age" would stand a test
I guess her knowledge is probably based on her curious and reflective nature and perhaps partly on the fact that she spend most of her life in the Mysterious Beyond. There she probably lived a semi-nomadic life, that is she and her family were traveling but only within a limited area. That they were traveling rather than settled in one place is suggested by Ruby's knowing that her family will be at hanging rock on a particular day and that they are living within a limited area is suggested by the fact that Redclaw seems to be such a problem for them. They could just move out of his range if they were "far-travelers".
I think you Austin (landbeforetimelover) are the severest critic of Ruby. If memory doesn't fail me you once described her as "eudaimonia" with regard to the fact that she seemed to "enjoy the mud too much" in "The Mysterious Tooth Crisis". I am not really sure if enjoying being happy and enjoying to enjoy things is really a "flaw of character". You even have it in your declaration of independence as the "pursuit of happiness". I admit that she looked a bit drowsy in that scene, but what's wrong with that? It's not like she had taken some illegal drug or something.
One funny thing I notice is that even though you criticized Ruby for being eudaimonia, you still chose a picture of her looking very much like that for your signature.
I guess I can relate to Ruby as she shares some of my own quirks while it may be more tricky to relate to her for anyone who does not.