it's not polish singing you ostrich
Ban claw, he called me an ostrich.
I really, really, really hate being called an ostrich.
so on the one hand calling a person a random noun cannot be said to be necessarily hateful, e.g. what if I called someone a cupcake? it's just silly & nonsensical.
otoh there is a precedent for calling people animals in a derogatory way. e.g. cow, pig, rat, snake, etc. however, these are also established colloquial associations that draw parallels with negative qualities real or imagined of the referenced animal. so how to react in the situation where a random, unassociated animal is mentioned? this would seem to fall back into the silly/nonsensical category. e.g. "whatever you say, you otter"
we can also consider that there's a counterposed standard for non-hateful usage of animal names, e.g. "you silly goose". common sense tells us that this is a playful, nonmalicious comment, though the recipient could technically make an argument like "geese are unintelligent creatures, I feel like the person was implying I'm unintelligent".