The rules for this showdown according to Letterboxd's announcement: "Make a Letterboxd list of your ultimate narrative features starring at least one animal in a leading role (spoken or otherwise). Remember to tag your lists so they are counted in the consensus! showdown:animalfarm"
Honorable Mentions: I did not include Jurassic Park and Jaws because for me they did not feel like the animals play a leading role. In Jurassic Park there are many different dinosaurs. And in Jaws you don't see the shark that often. King Kong is too monsterous to be counted as a normal animal. And Rocket Raccoon from Guardians of the galaxy is an alien.
Movies I need to watch again but I think they could have made the list: Watership down, Homeward bound, Beethoven, Felidae, The Bear, Chicken Run, Antz, The Land before Time
The Letterboxd community list: