The Humans in Five Nights at Treasure Island are characters that are human and have at least some importance to the main storyline.
Jake is the player character for Five Nights at Treasure Island. He was hired to work for the SSA as an intern under Greg and Lisa after Henry went missing in Pirate Caverns. He is the only human on the island during the events of the game because of the team's small budget caused by going back and forth searching for Henry.
Greg is the phone caller who works for the SSA above Jake. He calls on Night 1 and explains many of the game's mechanics as well as some of the game's plot. It is worth mentioning that he hints at Henry's existence later on during his call.
Henry is the intern that got lost in the Pirate Caverns after Lisa was not supervising him. It is theorized by many that his remains got scattered into the Suits.