How would the world animal pollutions of today compare to those of say‚Ķ. 999BC? 

Would they be far higher in most cases as I assume, and if so is man defiantly the cause?

Humans have definitely had a dramatic impact on world ecology, and this has certainly affected animal population sizes -- for both good and ill. Thanks to humans, many species are now extinct or on the verge of extinction; but it's also thanks to us that cattle and sheep are far more numerous than before domestication, and rats have a global distribution.