would it have been possible for the revolution to happen without animal-ism?

The animal figures or the animal characters in George Orwell's Animal Farm are actually a depiction of the human traits and attitudes. The prime reason for the revolution to take place was indifferent and pitiable treatment of the animals. If the animals had decided to let their master treat them as "animals", they would have continued living in that same inhumane condition starving and thristy untill they eventually pass away. The very fact that they left their "animal-ism" and decided that need a better life is the reason for the revolution to happen. Orwell has shown various animals with different human and with such mastery that the book became an instant hit.