Why was the case Plessy v. Ferguson important? It was the first time that anyone spoke up against the practice of segregation by race in the southern states.
It showed how Homer Plessy used his background as a free man of Creole descent to argue the constitutionality of the law and win his case.
It provided a way for states to legally segregate races and paved the way for the widespread use of the Jim Crow laws.
It allowed blacks to ride the train cars equally with whites without any segregation in place.