The correct order of key events regarding the exploration of space, beginning with the earliest, is:
- First humans in space (Yuri Gagarin in 1961)
- First humans on the moon (Apollo 11 in 1969)
- First space shuttle flights (first flight was in 1981)
So the closest option from your list that reflects this chronological order is:
first humans in space, first space shuttle flights, first humans on the moon.