Dialog choice, or the words your character uses to describe the world around them, is a major deal breaker for books. If all the characters sound the same they lose their individual personalities. One of the big places where you’ll see a variation in a shared language is in slang words. Slang changes much more rapidly than the rest of the language. It’s okay, sometimes encouraged, to create slang for your new world.
Negative slang usually reflects major religious beliefs and social fears (damn, hell, comparison to being a dog, or stupid). Positive and affirmative slang is less codified but usually comes a subculture of some form before being adopted and adapted by a wider group of language users (wicked, cool, hot, lit, ect).
Buzzfeed did a pretty decent video on the evolution of American slang. Keep in mind that what you’re writing isn’t 100% American culture so your subcultures are going to be different. Even within our culture slang can vary by family or friend group. They can come out inside jokes or even typos. So, while you’re writing, make sure the slang you use is appropriate for the time, venue, culture, and character using the language.