What does a raccoon ain't nothing but a big cat mean?

A racoon is a furry animal a little larger than the size of a domestic/housecat. what this sentence means is that a racoon is very similar to a cat. It could also possibly mean this in a defencive way for racoons, because racoons are known for carrying deseases and being unclean creatures and cats are clean and more loved than racoons. so the racoon is therefore stated as clean and as loving and ntelligent and possibly as agile as a cat.

in all this statement is defending racoons and saying that they are not as bad and filthy as they seem.