Humanity hasn't changed much; the tech level is a bit higher, especially for military technology, but that's about it.
A world Government was created which is largely ceremonial as the nation's leaders still hold the majority of the power. For instance, when contact with the aliens known as Stishak was made, the leaders of the larger countries met in back rooms and hashed out deals over time with the Stishak representatives rather than allowing the Earth President to do anything.
The Officer's role is to organise the squad, point out when to attack and keep the squad's spirits up. As well as the Heroes, the Officer has a fresh supply of Crimson Shirted Rookies to ensure the mission is a success.
Commands three crimson-shirted rookies who will always die before the main characters get in trouble
Can take an action to allow an ally to attack