Most of my characters are non-human extraterrestrials. Humans repeated a lot of history when they invaded the rest of the galaxy. Every species has flaws and strengths. Every character is a mix of good and bad traits. Even the worst of the worst are (or believe they are) doing the wrong thing for the right reason, and the best of the best screw up at the worst times. I really don't want to criticize humanity, put the aliens on a pedastal, or vice-versa. Any advice on how to get the true complexity and balance of my characters and plot across to readers? It's YA science fiction. Right now I am writing scenes and seeing what my characters do, but I don't want anyone to sound or act preachy. Especially my MC, because everything is from her point of view, first-person. Thanks for your help.