First introduced in Five Men in Normandy, the concept of the Goon from Five Parsecs bears a bit more discussion:
Essentially, we divide the people you may command and encounter into two broad groups:
Characters are the movers, shakers and personalities of your games. Usually, a character will be fully detailed with a background and motivation.
Any figure that has been given skills or other unique abilities is automatically a character.
Goons are then the vast, teeming masses of humanity (or alien-kind). A goon usually has a name, a weapon and that may be it.
Goons might be more fully established with motivations and backgrounds or the player may fill these in later in the campaign.
A goon will never have skills or other abilities however.
In "Five Men", they make up your regular soldiers. They will fight reasonably well and obey all the general rules that apply to the game.
In "Five Parsecs", they're the various crooks, adventurers and plain old civilians that you find anywhere you travel.
The basic stance of FiveCore is that a human is just that: A human. Everyone fights according to the workings of the basic game rules, unless they have an ability or trait that changes things. The goon is simply a thematic way of defining those figures.