Yes, the Society hasn't stated that animals were once "perfect" or lived forever. Your point, Pterist, about how Adam and Eve would know what death is, from observing the animals dying, was a point made in some talks when I was a JW. This made me question, as I was growing up, why God just didn't seem to give a damn about animals. They can feel pain and fear like we do, but apparently it's okay if they die violent deaths or die from old age? I gradually realized that the brothers at the top of the organization, and any elders that were good company men, had a positively sociopathic attitude towards animals, since they were imitating what they thought was God's mindset towards them. It was one of the first red flags for me about the religion.
I thought from the title that this thread was going to be about death of humans in paradise -- how, if you enjoyed taking walks in nature in the new system, sooner or later, statistically speaking, you would die by having a tree branch fall on you (or by sliding down a hill and hitting a rock with your head, etc.). As you took nature walks over a thousand years, a million, a billion, the likelihood of death by tree branch would approach 1.