What caused the animals to end up being an exact copy of humans?

Why do the pigs want/choose to portray (this might not be the right word haha) human-like actions?

First of all actually, did they PLAN on doing that?

The rebellion stood for the rejection of the corrupt lifestyle of humans; it was all destroyed by the pigs. Why though? Were the pigs 'too into their own world' that they did not realise they were mimicking the humans? OR was if because of Napoleon's mindset of ruling Animal Farm his own way?(this is getting kind of out of hand huh) OR does Napoleon simply want to have a better life?(human actions like drinking milk, sleeping on beds etc are way more comfortable than how the animals live)