Animal fantasy is not well developed as a genre. Let's survey the lay of the land. What's out there? The aforementioned Redwall books (mice, badgers, hares, other stalwarts of the English countryside). Dunston Wood (moles). Watership Down (rabbits). Mouse Guard (which I believe may be something to do with mice). Alan Dean Foster's Spellsinger books (which I haven't actually read - something about otters?). The Rats of NIMH books. Most if not quite all of it involving pleasant familiar mammals who act either entirely like humans or with a certain character trait exaggerated (rats are sneaky, mice are ironically brave, and so forth). The Dunston Wood books and Watership Down make certain attempts to get inside the heads of moles and rabbits respectively, but those seem like outliers for that reason.
Where are the animal fantasy settings in mangrove swamps, African savannahs, Patagonian wilderness, New Guinea rainforest, Canadian tundra, Siberian taiga? While we're on the topic of crabs with their bludgeoning damage of 1, picture a society of crabs in a mangrove swamp. Several times a day the tide comes in and out and fundamentally changes everything. Big predators - fish, monkeys, etc., might strike at any moment. There are other mud dwellers (mud skippers, insects and so on) who could be allies, rivals, or something else. What would an intelligent society of such crabs look like, and construct? What is crab magic like? Do intelligent crab societies actually have druids?
I was joking about the secret game in 5th edition, but I am serious about the potential for animal fantasy to be a billion times more interesting than it is. Good fantasy and science fiction often involves taking a set of weird and crazy assumptions and then treating them as though they are absolutely serious and following through on them accordingly. You can boil this down to something even more essential and basic and say that good speculative fiction typically involves postulating a set of strange elementary principles and asking: what next? Hence: all the animals on the African savannah are as intelligent as humans and can also do magic. What next?