[Astromancer]

{The Farfarers}

Try this idea.

Millennia ago powerful aliens noted the Earth's abundant lifeforms and seeded the galaxy, which was mainly sterile, with Earth life. With the rise of the classical civilizations, they decided that Earth life was ready to develop on its own on the many worlds they'd spread it to.

Many of the Human and Near Human groups that these seeders took from Earth were further manipulated genetically. The resulting parahumans then went on to found civilizations of their own.

Now, in the Twenty-Fifth-century humanity has developed two forms of FTL travel. The first is a jump drive. It goes from jump point to jump point instantly. The physics governing how many jump points a star has and where the jump points go isn't understood. However jump points are easy to find and cheap to use. The second and more expensive type is the skimmer warp. The speed of these systems comes in quantum levels. Warp quantums allow you to travel at the speed of light times the cube of the warp level. Example: WQ5 allows travel at 125C. Skimmer Warp is expensive to use and requires high maintenance and actual travel time. But it is far more flexible.

Humanity moved out to the stars quickly and met our kinfolk.

This can go as you like it. Traveller with the numbers filed off, STOS, Doctor Who, Lensmen, whatever. The aliens are in fact simply humans, and you know what trouble they are. I'll add further details later. This is a base I intend to use a few times.