Great Old One
I was thinking the best way (for my groups) would be: a group of epic-tier heroes defeated the Evil Gods about ten years ago, and goblinoids are no longer forced to be evil (any more than humans.)
Why ten years? Long enough for word to have gotten around - goblins are no longer kill-on-sight - but not long enough for a new normal to have really established itself. Goblins don't have a morality or religion anymore; some have embraced one or another, but as a group they're a bit aimless. Older goblins default to the old ways of being, younger ones actively seek new ways. Older non-goblins still have the same gut reaction (though they generally know better than to act on it), younger non-goblins don't have a stereotype to fall back on.
So if anyone's playing a goblin: it's about defining what they are, because right now no one knows.
It's a good principles, and another thing that I like in the principle of Hero Quests to change myths, there is always the butterfly effect of making changes that were unintended. This is where the God Learners really messed up, actually, but still managed to have things somehow holding together despite side effects. So maybe the goblins are no longer evil, but halflings now are (very scary thought).
Or maybe the adventurers discover the effects, but realise as adventures go by that it's them from the future who caused the effects. What will they do ?