The Earth exploded along with the rest of the solar system long ago, but before it died, the Earthers had time to send out huge fusion slowboats packed with colonists out to the stars. The fastest ship took 1200 years to get to the Cluster. Now, 500 years later, the slowest one hasn't yet arrived. Humans flourished in the Cluster, their technology eventually exceeding that of old Earth. Now they have built up a web of commerce and association based on the Jump Drive. There are highly advanced aliens in the Cluster, and relatives - like humans, descendents of Homo Erectus who were kidnapped by aliens, along with chunks of Earth biota, a million years ago. A very high tech, but not post scarcity, setting.