In Octodad: Dadliest Catch the protagonist is of course a perfectly normal human person who is not at all an octopus in disguise.

More RPG findings:

The Elder Scrolls series feature playable lizardlike (argonian) and catlike (khajiit) races, and the world has a lot of lore related to them. The Elder Scrolls III: Morrowind and The Elder Scrolls IV: Oblivion both include them, and the older titles Elder Scrolls: Arena and Elder Scrolls Chapter II: Daggerfall (which you get for free if you purchase Morrowind/Oblivion) also have those races as playable characters.

In the Ultima RPG series, in Ultima VI, Sherry the talking mouse can become a party member. She also appears in Ultima VII but cannot become a party member there. Ultima VII also includes a talking unicorn, and talking simian creatures called emps. Moreover, Smith the talking horse appears in several Ultima games: main games IV-VII; he also appeared in the Martian Dreams spinoff but only in a dream sequence.

Kabuto is a monster. As you wrote "A creature can be considered an animal" i thought this may fit your description (?), because a monster could be considered as a creature. But i guess, that this game doe not belong to your list, as its much more a monster, than an animal.

Bear with me: well, to be precise, the protagonists are all ... toys. But: those are a bear, a shark, a pig etc .. And as you play the bear sometimes he is very much alive and talking. One would not have the impression that it is a toy.
But yes: if you are looking for animals in the literal sense, then that is certainly a gray area.

I would add RiME. The fox is not a main character but it's a big part of the game. And the second chapter features another animal as a "villain".

Actually, in Ultima 6 (PC), getting sherry is mandatory, as you need her to get a certain quest item. Most players tend to leave her behind due to her having lousy strength (too low to even wield the most basic of weapons) (and apparently she can't be revived), but she is usable if you level her up, preferably if you level her at the Shrine of Valor.

In SNES Ultima 6, she is no longer a party member and has been relegated to just being an item.

Thanks for the clarification! I wonder how many keep Sherry in the party all the way to the endgame?

Another Ultima game with animal-like anthropomorphic characters is Ultima Underworld: The Stygian Abyss, where there is a group of lizard people. The Avatar needs to learn their language for at least one plot-related quest.

I'm actually intrigued by this, how does this work? Did I miss a feature where GOG/Galaxy allows you to view/sort by custom tags assigned by other people?

Mutant Year Zero: Road to Eden
Detective Gallo
Chicken Police

Ancestors: The Humankind Odyssey?

Some more:

In Spongebob Squarepants: Battle for Bikini Bottom the main cast are anthropomorphic sea creatures (sea sponge, sea star) and a squirrel.

The main characters of Chook and Sosig: Walk the Plank are "a sensible ghost chicken and a spaghetti cat".

In Night in the Woods all the characters are depicted as anthropomorphic animals.

Elder Scrolls games - Kahjiit and Argonians

Alba: A Wildlife Adventure
Chicken Police
Niche - a genetics survival game
Inherit the Earth: Quest for the Orb

Earthworm Jim 3D. There is a worm, cows and a crow from what I remember.

Also Moorhuhn games (known as Crazy Chicken in english). In most games, you either play as or shoot birds (willow ptarmigans). And in some of the games, you can also play as a frog, mole or turtle.

Rayman's Raving Rabbids?

Owlboy
Dust: An Elysian Tail
Ori and the Blind Forest
Kero Blaster
Legend of Kay