The Guest Area is where you are in the 4th chapter of the game. All throughout the location, you can see people, full of greed, chomping on large steaks and sausages. Three times in this area, you are chased by the guests. If you jump on their heads, you may confuse them, but other times they cannot be tricked. Whenever you are caught in a guest's grasp, it is inescapable and you are shoved into their mouths. Something that people are confused with is if the guests are wearing masks, like the chefs. This is not confirmed.
The Lady is in control of the Maw and is what keeps it going. Without the guests, the Maw would be a sad, desolate place in disrepair. The guests themselves are important. You see the guests twice in Little Nightmares, at the 4th chapter in the Guest Area, and at the very end of the game when you have taken The Lady's power. You walk down a small carpet, killing the guests with the power as you walk by. This is the last part before Six is seen outside The Maw.