Q: "A cowboy on a horse at a rodeo." Does this mean that "A cowboy is riding a horse at a rodeo."?
A: yes

Q: "Guitarist and drummer on stage at a concert." Does this mean that "The musician tune up their instruments"?
A: it is not possible to tell

Q: "A motorcycle goes by a crowd with its rear wheel in the air." Does this mean that "It's a woman"?
A: it is not possible to tell

Q: "A young man jumps up off his skateboard on the street in front of a house." Does this mean that "A man jumps up off his skateboard on the street in front of a house."?
A:
yes