300 years ago, if a fisherman got eaten by an orca, would that have been recorded as "eaten by an orca" or "eaten by a fish/sea monster"? It wasn't until the mid 18th century that cetaceans were asserted to not be fish, it took another century or more for this perspective to permeate popular culture.

For instance, in Moby-Dick (1851) Herman Melville dedicates an entire chapter to explaining the taxonomy of cetaceans and says they aren't fish because they breath air, have lungs, have horizontal tails, etc. But then he says whalers scoff at this distinction and consider them fish because they live in the water.