Your argument is completely one sided and doesn't take into account that humans are also everywhere already and would be just as ready to strike, only with weapons. Other than domesticated animals, there really aren't that many large mammal/reptile populations in the wild. So we'd be looking at an army of cats, dogs and cows. The cows who herd would be EASY targets since they're cows and stupid and carpet bombing would literally kill millions of them instantly.
Cats are too small to really do any damage unless they're in packs and even then a pack of humans > pack of cats. Sure a single kitty or two may scratch me up pretty bad, but the moment i grab hold of one, its instant kitty death.
I'd say dogs would be our biggest threat but even then, half of all dogs are little yipper dogs and they'd die quick. Not having opposable thumbs would be their downfall. Most dogs would be stuck in houses or yards and it'd simply be a matter of going house to house with guns to win that fight.
Ya, humans would win, and fairly easy.
Think about it..a car is literally a one man indestructible killing machine against pretty much any animal. Imagine a tank. A single tank could wipe out every animal in africa given enough time.