Will, you’re preaching to the choir re characters. You may remember one of my writing mantras: “Start with character. End with character. Find the story in between.”
What I especially resonate with your comments here is this idea of making sure to ground the character in their world experience. This speaks to the totality of who the character is, everything from personal history and backstory, to the way they talk, to their world view, and on and on and on. As I mentioned previously, that is one of the aspects of Zootopia which makes it such a strong story, how the storytellers REALLY immersed themselves in that story universe and the lives of their characters, then zeroed in on key dynamics to create clear, focused characters who are entertaining as well.
BTW I just read where Zootopia won the Critics Choice Award for Best Animated Feature. Just based on what I’ve read in the script, well-deserved.