By unanimous vote, the choice falls to you. What animal do you choose to send and why? it can be the baby form of the animal or the fully grown adult version.
I’d send a very large taxidermized elephant. Beam it straight up to their mothership. When they claim that it’s not very cute, I’d provide a long-winded pseudo-philosophical diatribe about the meaning of cuteness and how they should not be so quick to pass judgement. While their council convenes to decide our fate, the world’s greatest covert operatives exit the elephant through a carefully concealed trapdoor in the bottom. They commandeer the ship. Let the counter-invasion begin.
Cats enslaved humans. Pretty sure they’ll do the same to aliens as well.
I’d go the classic tried and true, regular ol’ puppy. They won humans over, maybe they can win over the aliens as well. Better make it a Basset Hound puppy just to seal the deal.
Red panda is the obvious answer.
A quoka
