Why is my character just standing and not doing anything?
The character may be in drafted mode (Manual control). Select the character and then click the undraft button to set them back to automatic control. Do not keep characters drafted unless you want to move them around manually. Draft is mostly meant for combat situations and specific situations like equipping them or carrying another wounded crew member to a medical bed. All normal tasks found in the priority menu are performed automatically when the characters are not drafted.
The character may be on leisure schedule or sleep schedule. Select the character and check their information.