It certainly didn't start with 80s cartoons - anthropomorphized depictions of animals feature among the oldest written works. Aesop's Fables are 2500 years old, and the geographic dispersal of similar stories indicates that they originate even further back than that.

Sure, but it was 80's kids who started tuning in every week, nay, day, and forming emotional attachments with cartoon animals.

Austin Osman Spare did it earlier than that, as did some of the old greeks and others.