What is this thing called the Cosmic Storm? It's a natural phenomenon that doesn't require extremely advanced tech to transport living things in a galactic setting.
To the space traveling peoples in our galaxy, these phenomena are known as the cosmic trade winds. There are several currents running throughout the galaxy. The set of trade winds called the cosmic storm has an orbit which includes the planets Earth, Nenmar, and Gatton.
These trade winds are somewhat analogous to the Gulf Stream in the Atlantic Ocean on Earth. As the Gulf Stream is a current of water inside a larger body of water, so the cosmic storm travels in an established circuit in the galaxy. It loops around to repeat the cycle throughout the life of the galaxy.
No one knows what the cosmic storm is orbiting around. However, it is known that the pulsating star near the center of the galaxy marks what is called the heartbeat of the trade winds.
Because the trade winds are so predictable, spaceships can "ride" them. That's very convenient for space flight in the same direction, as spaceships can conserve their power to use for other purposes while in this configuration.
There also are other inhabited planets along its path, and the trade winds occasionally sweep up organic matter from one planet and deposit it alive and intact on another. In this process, the trade winds carry and exchange like materials among similar planets. This has resulted in life forms on the different planets being not only similar, but actually genetically compatible with each other. There are countless peoples like humans, Nenmarans, and Gattonians all over the galaxy. They're all compatible and able to interbreed. Peoples from several planets distant from each other already have successfully blended together.
A few of these peoples, such as Gattonians, have learned to travel through interstellar space, but most are not space travelers at all. The propulsion problems can be solved—it's the time versus distance problems that require knowledge of an additional dimension of tangible existence that is not easy to explain in a single sitting.
Things, and people, that travel through the cosmic storm are pulled through that dimension of existence.
