2018’s Record of a Spaceborn Few is the third volume in Becky Chambers’ Galactic Commons series.
Having ruined the Earth, humans mined the Earth’s cities and turned them into a vast interstellar fleet. The Exodus Fleet’s design proved surprisingly robust; not only did the fleet survive centuries and light-years, the people riding the ships neither went mad nor devolved into cannibalistic barbarians. The Exodus Fleet was an impressive achievement. Even if the technology involved was hilariously backward by galactic standards.
If only humans had encountered the galaxy-spanning Galactic Commons (GC) before the Fleet set out, the whole endeavour might have been unnecessary. As it is, the human race was allowed to join the GC as a very junior member, while the aging Fleet was graciously permitted to park itself in an otherwise useless stellar system.
Where it still orbits.