For instance: The white man moved into the Americas, and after a few skirmishes and growing pains, we now all proudly call ourselves Americans, and give no thought to the original inhabitants of this country. Sometimes I wonder what this country would be like if we, the white man, had been repulsed. Assuming what we see out the window, the cities, the economy, and the communication system we have today, are the same, how would things be different? How would my stories be different if the original Americans were the dominate peoples of this country? How would this difference affect things around us?
The whole fun part about writing fiction is to play with ideas like this, but you have to remember your history, or create one. Past has an effect on present. Present just doesn't appear on your page by some miracle. Even if you absolutely never say a word about the history behind your story or your world, it should still be there; it should influence the decisions your characters make. For instance, Joe Blake, who lives on first street, in AnyCity USA just might act entirely different from John RedFeather who lived on that same street in that same city, simply because their entire history would be different.
In the same respect, your blue-skinned, vaguely humanoid character from Gidi Prime will also have some kind of a world history, or country history, or at the very least, history of society, and just like Joe Blake or John RedFeather, their decisions will be affected by it. Who knows, maybe their entire breed will have been dictated by the demands of their history.