The correct order of key events regarding the exploration of space, beginning with the earliest, is:
first humans in space, first humans on the moon, first space shuttle flights
This order reflects the timeline of key milestones in human space exploration:
- First humans in space - Yuri Gagarin's flight in 1961.
- First humans on the moon - Apollo 11 mission in 1969.
- First space shuttle flights - The Space Shuttle program began in 1981 with the launch of STS-1.