Okay, I know that a lot of people have been confused about the use of animals in the new AOT opening, but there is a purpose for this! It's to show that titans can be compared to other big predators. Remember, the staff for this anime love to add a ton of symbolism to the show. Just look at the second AOT opening!
Squidding Awesome! Sentai Filmworks Will Dub Second Season Of The ‘Squid Girl’ Anime