I believe every group starts an adventure with a ship. At least that is what it has sounded like. During combat the PCs will have different jobs to do. The pilot steers the ship, the gunner fires the weapons, the engineer makes repairs. They wanted to do it that way to avoid ship combat becoming 1 player doing everything while the rest of the group sits around waiting for the fight to end.
I also read that ships will have customization options which players can use to upgrade their ship, or even potentially build the ship from the ground up.
I would have to say Humans first. For the same reasons most others have mentioned. Easier to connect with sort of thing. As for Starfinder I think I would most like to try out the Ysoki. Playing a rat-man could be a fun experience.