No they did not
Once Giants Roamed the Earth was created in 2005.
There Are Giants in the Earth was created on 2004-10-26.
Giants in the Earth - opera - was created in 1951.
In most contexts, "earth" is not capitalized unless it is being used as a proper noun, as in "Earth" to refer to the planet. So for your example, it would be correct to say "walk on the earth" with "earth" in lowercase.
No Yuri Gagarin did not walk on the moon. But he only orbited the earth once in the year 1961.
There is no evidence to support giants ever existing. Giants are merely mythological creatures.
Walk off the Earth was created in 2006.
Curtis Keaton
1927.
The gas giants are important because their strong gravity draws in many large asteroids before they can hit earth.
Because, giants can only occur once they leave the main sequence.