I believe that character.png is not an original texture and thus you must credit and verify its license.
I also have the same concerns regarding crosshair.png and object_crosshair.png
Please correct me if I'm wrong or let us know if these textures (or any others) comply to the appropiate licensing and crediting.
I've myself created the character.png ,crosshair.png and object_crosshair.png. But yes, I've edited the character.png from base texture (wtfpl license).