I don't have a Reddit account so I'm just going to share a random way-too-into-this-whole-MCU-thing-no-wonder-I'm-unemployable theory:
Asgardians call Rocket 'Rabbit' correctly, when they first met humans one of them brought a pet Asgardian Raccoon (referred to as a Rabbit), the word entered the lexicon but given this was the Old World and Raccoons are a New World creature, memory's faded and it got co-opted to our fluffy friends / pests today.
p.s. one immediate benefit from this far-too-deep thinking on this issue, I finally have a nickname for my Minccino, as Chinchillas are famously also not rabbits!