A racer or a jockey.
A person who is of three different races is commonly referred to as "multiracial" or "tri-racial."
The person is called a Marshal.
multiracial or of multiple races
A member of the pit crew.
I believe the person who rides the horses in the races is called a Jockey.
longboard races
A person who rides horses (mainly thoroughbreds) is called a Jockey
The gun used in running races is called a starter's pistol.
Oaks are races for fillies or mares
regatta
motorcycle races!! each individual race is called a moto
The equestrian