The correct order of key events regarding the exploration of space, beginning with the earliest, is:
first humans in space, first space shuttle flights, first humans on the moon
This sequence includes:
- First humans in space (Yuri Gagarin in 1961)
- First space shuttle flights (the first flight was STS-1 in 1981)
- First humans on the moon (Apollo 11 in 1969)
It appears there was a mistake in the first answer provided; the correct answer reflects the accurate timeline.