(Let me try it now from a different angle... )
We are social creatures. Not only are, we MUST be social, in order to survive from the longer point of view. Good and Evil could be thus interpreted as what helps and harms our social being. (Again the Robinson Crusoe thing: can you be Evil if alone?)
This can be easily separated: if we take only one group/tribe/nation into account, what helps and harms is the groups Good and Evil, so to say. To take Captain's silly example, Monkeylanders that dance under the moonlight are a threat to the Crocodilians social integrity, thus will be marked as Evil.
That was a kind of "relative" Good and Evil, if such a thing exists. How to approach the "absolute" Good and Evil, something people should really strive for? Perhaps it is the social being (and in the end survival) of all members of the race. Let us ignore for the moment all complications that arise, if we have several different fantasy races at hand.
Should the Crocodilians learn to dance under the moonlight, to make them better people (nice dance=less stress, etc), or should the Monkeylanders forget it for their own good, since it destroys their morals, their health, or something? Or shall they learn to accept their differences? Or is there a special reason, why Crocodilians don't dance at nights? (stray undead, cold nights & the flu, hot nights & mosquitos, a curse, promise to a god, ???)
I can't work out, what is proper and better for everone (or maybe this "global" point of view is unusable...), but this could be it: Good is what enables our race to survive in the long turn. In the short turn, it means simply not destroying our society. In the long turn then, making it grow and adapt.
But if there are multiple distinctive races, what would be the ultimate Good? If we consider them all a part of the same ecosystem, something like a peaceful coexistence, not endangering anyone to extinction.
But once a _different_ race from another planet arrives, all this turns again on its head. What is right then?
I can imagine a different kind of nationalism, in a larger scale: it is a whole planet, and its ecosystem, that is to be loved and protected. And more could be done: since it is their ecosystem that is superior to any other, they would naturally try to transplant it elsewhere. Thus the friendly Ximbarans arrive, trade with us, research our ecosystem, and "forget" a few well-picked plants, that spread, and spread...