Some of them found their home solar system ‘too hot’ for them due to accidents, unpaid bills, various non-legal organizations searching for them, some looking for better paying jobs, and some just liked to travel.
More than one solar system supplied crew for this ship.
This does lead to the problem of people with the same or similar names. Some of them could be people making up a name to hide from those looking for them, or coincidence. Some planetary governments didn’t like the idea of identity numbers, so there was no real way to tell people on the ship with the same name apart.
But they were wrong. They were identified as their name, the ship’s port they arrived at, and the standard date and time they arrived. While it didn’t stop all duplications of names, it did stop most of it.