What is known about the gods is that they existed before the world and created the world in council, and that they are still present but largely hands-off about the world unless specifically asked for stuff (hence divine magic, which incidentally Tirgul frowns on because they see it as a threat to their power).
In a Discworldly fashion, Kelenore’s gods grow and feed off belief, so gods with small cult followings or very passive congregations won’t be as powerful or influential as gods with huge or really devout churches. In this way, it’s possible for a god to be forgotten, its power and existence stripped to nothing; and it’s also possible for a mortal being to ascend to godhood (hero worship, or hallowed sites gaining their own godhood from the power of people’s reverence to them). It’s not known how the creator gods mustered the belief necessary to be powerful enough to create the world – if there was someone or something that believed in them from before time, or if they were created by something greater, or what.
Not all gods are anthropomorphic – goblins, for example, revere the sucking mud and swamp diseases and predation from monsters without giving these things names or faces – though personifying a belief makes it easier to focus belief on, so anthropomorphic gods tend generally to be more powerful. Similarly, things that a great many people take for granted and believe without questioning are often endowed with god-power, e.g. the cold, howling wind and biting, blowing snow at the peaks of the Ered Naugmar can be effectively prayed to, because everyone knows the Ered Naugmar are cold and windy. These law-of-nature gods are where most Druids derive their magic from.
Greater gods can lend some power and influence to lesser gods with similar portfolios, if they deign to; e.g. Lolth, who wields the belief of an intensely devout church with a huge congregation (like the entire underdark at least acknowledges her), might decide to join with and empower the goblin god “culture surrounding a fear of spiders,” which is a concept that a relatively small population (there aren’t nearly so many goblins) takes for granted.