The U.S.S. Lexington was originally going to be the first level of Resistance: Fall of Man.
The U.S.S. Lexington was meant to be introductory tutorial level. Nathan Hale would start off in the ship and navigate his way around the vessel learning about the Chimeran War from those onboard and doing some weapon training before joining his squad on a U/AV-17 Hawk and flying to York.
The level was created, however, Ted Price states that Insomniac Games "could not get the level done" so decided to pay homage to it as an opening cinematic and a multiplayer map. Due to being converted into an online map, most of the level was cut out of the game files, entry points to parts of the ship are now sealed ship doors. However, the control room, downstairs within the ship is still accessible.
It is believed that Hale would have encountered cut character General R. Hadley onboard this ship, as the General has Robin Atkin Downes as a creditted voice actor for him.