Linux's roots go way back before the birth of Ubuntu. In fact, Debian was among the very first Linux distros to b in the wild. Just as the nineties represented rock 'n roll in its gnarling middle age, so the computer age and the dot com boom really stepped the forward pedal hard towards the Information Era. Midst these times was Debian, the brainchild of Ian Murdock and Debra Lynn (get it? Debra Ian).
The philosophy of it is purely simple. Debian came about to competitively rival with commercial OSes while being free. Behind the wheels and mechanisms of Debian is the work force of volunteers from all over the world, collaborated by the experienced and the inexperienced, software experts and prospective developers. Also it's a project, bent for people out there in the world who wants to make software better and well-maintained by the handful of the many, not the few. This makes source code accessible and worth learning from. These volunteers, tied to a strongly knitted community, share a common vision for the world to realize.
Debian carries the spirit of Linux very well. Also, it is the upstream that almost all Linux distros, including Ubuntu, relies on heavily. To become a contributor requires a lot of self-motivation and initiative. For instance, it is not expected for a prospective contributor to become a core member overnight or be handed the skills of writing code on a silver platter. This is a process, and contributors - you are always welcome - should be ready to take it on.