Im glad you like where the project is going and THANK YOU for helping while being so busy :). Yes, you are in charge of the creation of the main character. I'm creating all other static meshes (easy!) and already started creating the initial levels.
I had in mind a futuristic character (could be an android but it doesn't have to be - whatever you feel would go with the mechanics and aesthetics of the game). Please use the UE4 mannequin as a guide for the proportions and the UE4 skeleton so I can reuse it later :). As far as animations, they should be simple - walk, sprint, jump, hold / carry(for the blue cubes), and hold a gun.
Do you have an email I can use to contact you? I'm working on an early build of the game to send to the composer so he can get a feel for the game play while making the music and would love to send it to you as well :).