These 50,000 survivors, whose number are dwindling day-by-day, due to nasty Cylon attacks & plots, live in many spaceships. After the attack all of these spaceships assembled & formed a cluster around the sole surviving, old-generation, Battlestar named Galactica. These Spaceships have Faster than Light (FTL) travelling capabilities, and their route & destination is planned by Galactica's powerful supercomputers. The precise distance achieved in one jump is limited by the computing capabilities of the supercomputers. So greater distances are achieved in multiple jumps. But to make the matters worse, Cylons have infiltrated the human cluster, with their Agents among Humans, and have superior technology to compute at least 2 or 3 times the FTL distance, that the human technology could compute. Also on being dead a Cylon could upload/transmit his/her/its memory into a Resurrection Server and later be reborn with its intact memory but a new body of the same model who looked exactly the same.
Without hope, the Humans are on the run, and they sometimes fight back, with the sole purpose; survival into an unrelenting universe. The Humans have a small but an excellent fleet of fighter aircrafts and Fighter Pilots. But the fleet is losing their count in frequent fights with Cylon fighters and the replacements are hard to find.
Also the limited supply of water and mineral resources too dwindle very quickly. And hence Humans' major exploratory activities centre around finding water and mineral resources to satisfy their survival needs, instead of making an effort to find a suitable planet to survive biological life. The citizens are demotivated and susceptible to rumours & fears, while also being xenophobic to the possibility of Cylon Agents being among them.
But something is different. And while the humans are religious, who pray to the twelve Lords of Kobol, the Cylons too have found their religion in the form of one God.
But not all humans believe in the stories of the Lords of Kobol. The Lords are said to have made an exemplary journey, in the past, from a planet called Kobol, to the twelve new planets/worlds/colonies and possibly to a thirteenth mythical planet called the Earth. The religious text books of Humans are filled with prophecies and stories of these journeys. But some leaders of Humans find some resemblance in their current situation and some of the prophecies of their religious books. And so begins the search/effort/journey to decipher and retrace the path to the thirteenth mythical planet, which could sustain life.
But the Cylons too are interested in finding about the myth & the Earth. They could have left these decaying humans with their problems, but they didn't and Why?