The discovery of the Settled Systems' many oxygen-rich planets and moons meant humans could live just about anywhere... if they had the know how. You did, and utilized it to great effect.
Starting Skills
Geology
Newly discovered minerals mined from alien planets and moons have directly led to some incredible technological advancements.
Surveying
Humanity now has access to untold alien worlds, and the ability to decipher all that data while on the ground has become an essential skillset.
Weight Lifting
Weight training can significantly increse one's ability to carry weapons and equipment, both in space and on the ground