The alien living with you must be treated as one of your native-born. Love him as yourself, for you were aliens in Egypt. A priest, Levite and Samaritan all pass by. As Jesus was telling the story to a mainly Jewish audience they would have expected the priest or the Levite to stop and help the man as both of these would have worked at the temple in Jerusalem. However, Jesus surprises his audience by showing that it is actually the Samaritan who helps the man and pays for him to recover in a nearby inn.
Racial origins are irrelevant.
Jesus' point is that we should love our neighbour not matter who they are or where they are from. As the early church spread it actually faced a racial dilemma. At first Jesus' message was only told to Jews. As the church spread certain people felt it was right for non-Jews to hear the message and be welcomed into the Christian community as well. One such person was the Apostle Peter.