Terran

Terran's (humans) inhabit the planet Earth in the Sol System. They were the first species, other than the Old Ones, to build jump gates. The Argon originated from the Terran's as did the Goners.

Concurrent History
Earth history as you know it is the same up until 2007, when Japan goes into a recession. In 2011 Japan recovers and once again is a great center of research and innovation, with tech such as quantum computers and nano-tech being prominent, and the Earth becoming Bi-lingual with everyone speaking either English or Japanese.

From Sub-light to Past-light
In the year 2022, a student at Tokyo University accidentally discovers the jump gate principal while doing other research. Two years later experimental data shows that the jump gate principal can be used practically. The tests continue and soon enough in 2036, the first two "jump-gates" are built between Earth and Mars. With their success, another gate is sent to Alpha Centauri, with long range tests being conducted along the way.

The Void
While the Alpha Centauri gate was en-route, the lock between it and the Earth gate was lost. While scientist try to re-lock, they find that the Earth gate doesn't lock on to what they want, rather random locations throughout the galaxy. It is discovered that these are alien jump gates, connecting a block of linked, but uninhabited systems. The Old One's take notice of this and seeing Terran's as a theat, reconfigure the gate system to keep the Terran "threat" contained.

The Final Frontier
The Terran's, unaware of the gate changes, decide to see if they can colonize the other systems. They send probes through, but the data isn't enough, the probes can't conduct all the surveys they need. The response to this, send a manned vessel. The nations decide that they need a ship, a research ship, The Winterblossom. It's one year journey began in 2046

The Winterblossom returns to Earth in 2048,after a two year journey (which is one year longer than originally planned). They report to have found a system of dozens or hundreds of alien jumpgates but no intelligent alien lifeforms whatsoever, and no hints thereof, except the gates themselves. But they do find many planets that can be colonized.

Politicians create a budget for a Space Force in case of unfriendly alien contact.

Also, the possibilities of terraforming is talked through.

Prelude to Trouble
In 2059 The first ship of the new founded USC, United Space Command is stationed in Earth orbit to protect the planet from possible dangers (alien attacks are not publicly named as not to disturb the people). Nobody really believes in danger, except some paranoid military minorities.

In 2062, the first scientists, followed by their families, colonize the newfound planets