Aha, we'll guinzilla you are the guiniepig that was mutated in a weird experiment so he's here due to animal rights activists wanting him to have a good life

Autumnwolf you get woken up from your technology-induced coma every autumn to enjoy what's left of the world
I am a species confused intelligent cat that wanted so badly to be a wolf I couldn't stand reality anymore, and so I trapped myself in my own invention to live out my dream

Clanghostbear you are a bear that instead of getting inserted with a human-emulated mind you were given the essence of clans, the way of your thinking being of like a large unity of individual gamers coming together
Ratburn you were a rat that suffered 3rd degree burns in a house fire. Again animal activists took pity on you and gave you a better quality of life.
Joshua you were a cat who always dreamt of becoming a boxer, and when mind-reading technology was discovered scientists set out to fulfill your dream; unfortunately due to a mixup you were given the life of an RAF pilot and are forever confused
The simple, the best.