A Yoghurt on a Racetrack

While the Arks were a fantastic achievement in human engineering, compared to the rest of the ships flying around the galaxy, humanity might as well have been trying to pilot a yoghurt around a race track.

So, how were the rest of the galaxy already moving beyond the speed of light and establishing a galactic community?

Firstly, they had worked out a way to pull the wool over the eyes of the laws of physics. Secondly, they were professionals. The basis for galactic travel is entirely down to the invention of the Trebuchet Gates, and later the Starlight Drive and the far less elegant Ishimura Cosmic Drive. Astrophysicists in every species that have even approached space travel have butted up against the issues that an object with mass cannot travel at or beyond the speed of light. Albert Einstein was the human most often credited with working this out, although other species tend to prefer their own scientific celebrities. The first method for undercutting this particular immutable law of the universe was through the creation of the Trebuchet Gates. 

Very simply, a Trebuchet Gate allows you to instantly travel from one point in the universe to another by opening a wormhole and firing you through it at incredible speeds. The theory basically went that, if you just made the space you had to cross smaller, you didn't actually need to achieve light speed. Like a great many inventions, this one was sadly before its time. Since there was no other way to traverse vast quantities of space, there was no way to build a gate at your destination since you would already have to have been there. This meant that some hapless crew of explorers had to travel the old-fashioned way to assemble a gate so that others could cross the same space in an instant later on. Think of it like this: if you launch a plane from a runway, you need to know that there's another runway at the other end or things will go horribly wrong.

Nevertheless, they allowed for further exploration of your local star system but weren't able to take you further. 

The real leap forwards in galactic travel was the invention of the Starlight Drive. It is a miracle of modern science that still baffles the engineers who build and work on them. The problem with moving an object with mass faster than light is that you need more than infinite energy to do so. So, what the Starlight Drive does is that it converts an entire ship into a light-like substance (colloquially known as Starlight). This substance, according to all available physical tests, has a negative mass. Therefore, a ship can engage this drive and then accelerate well beyond light speed. However, this process is still quite energy intensive, so the vast majority of commercially available Starlight Drives need a period of 12 to 24 hours to cooldown between uses, depending on the model. Now, there was a way to cross vast swathes of distance without having to have already visited your destination. So many crews were ecstatic to discover this new wonder meant that explorers could strike out into the unknown, build a Trebuchet Gate, and then allow many others to follow in the blink of an eye. These networks of Trebuchet Gates all across the galaxy linked dozens of cultures together that would eventually become the first Galactic Federation, but that's a story for another time.

Of course, Starlight Drives came with their own set of restrictions. The largest ever Starlight capable ship at the time, the MSV Ishimura, embarked on its maiden voyage (1900 C.E) and engaged its Starlight Drive. The entire ship was torn apart as it only partially turned into Starlight. There were no survivors. Turned out that Starlight Drives had solved the mass issue, but could only cover a certain volume of a ship. So, the Ishimura Cosmic Drive was developed to move larger ships at the speed of light. The downsides of these drives compared to their Starlight cousins are considerable, but they are able to move enormous spacecrafts across the vast reaches of space. They require an average of approximately 56 hours of charge time before they can be used, run on expensive and single use fuel rods rather than cycling power, and have been known to adversely affect the health of those who work on them for too long. Some have referred to one such linked condition as "Turbo Cancer". There are a host of other issues but the Ishimura Cosmic Drive is currently the only viable way of moving a huge spaceship at light speed. Most people opt to either run these ships through a Trebuchet Gate or just build smaller ships and avoid them all together.

It is currently forbidden for any spacefaring civilisation to spread this technology to any culture that has yet to achieve space flight, fearing the destruction that a sudden technological acceleration could bring to an unprepared species.