Herein are various roles that could be played within a party:

Broad:
The Leader - one who leads. Includes making decisions, plans, and being charismatic or otherwise convincing enough to get people to follow. Includes having actual goals. Examples: Albert Renkarr.
The Mentor - one who guides. Generally involves having experience and knowledge of the quest at hand or the world in general. Example: Dionysus Berrywight.
The Student - one who learns and grows. Generally involves lots of character development and some skill at learning things in some way - either through investigation, research, or experimentation. Example: Avery Colzayre
The Maker - one who makes things for the party. Craftsmen likes smiths or carpenters, artists like songwriters or sculptors, or others like chefs or engineers. Example: Quacklin Grippytop.
The Source - one who provides a resource for the party. Can be anything from a rich character to a character with a specific talent or tool, like the owner of an airship or someone who knows every language. Healers, mages, and priests often fit here, as well as all fighters. Example: Davan Asher, provided fortune and airships.
The Gatherer - one who acquires resource for the party. Can be anything from a socialite, spy, or investigator for information to a thief, gambler, or merchant for money or objects, to a farmer, miner, or collector for other specific resources. Prophets and seducers fit here, too. Example: Arsul Toutant.
The Heart - one who handles the emotional dynamics of the party. Can be comic relief, a bard, an entertainer of some sort, a storyteller, a cheerleader or sidekick, a shoulder to cry on, or the second-in-command. A supporter. Example: Sidney Bronccour, Samuel Jericho.
The Motivator: one who is driven by a cause. Can be anything from a revolutionary to a person seeking revenge. This is the the source of forward momentum. Example: Genfyllid Cuniaid.

Other resources:
http://tvtropes.org/pmwiki/pmwiki.php/Main/FiveManBand

I can't find a source on the Bushman Hunting Party: Leader, Master Hunter, Joker, and Shaman.