There are two main characters in the game Josh and Anna. Josh is a delivery man who drives by with Special Orders in which you can earn rewards and coins by completing them. Anna is an engineer who helps you negotiate to get more contracts when you are selling your company, she's also the one who will guide you in the early stage of the game.
You can hire crew members and assign them to Ships and get additional bonuses such as Collecting Rate, Ship Speed, and Ship Cargo. You can choose to hire them from these three categories, Docks, Navy Academy, and Professional Navy. Each category has corresponding stars. Note that the bonuses you will get depend on Crew Stars.
Here are some example of the crew from each category:
Docks (1-3 Stars Crew Member)
Navy Academy (3-5 Stars Crew Member)
Professional Navy (4-5 Stars Crew Member)