Ideas for children story books!!

So for an assessment in my class, we have to come up with a story book for the age between like 7 - 12, or something like that and it needs to have a big political story line behind it. I decided to do animal endangerment and how humans kill animals just for what the animals might have since I feel like it’s a big topic. But I have no idea how to start it or end it 😭 I want the story to have quite a sad ending and that the main character is an animal or group of animals and it lowkey shows what humans do to these animals, but not being too obvious since it supposed to look like a children’s book. I have some ideas how there’s these water hole that the animals go to daily but then a group of animals don’t show up because the humans have done something to them and maybe an animal goes out and tries to see what’s happening. Idk all I need is some ideas since I have big writers block 😭