One-dimensional

Adjective

adjective

1. Having length, but no width, height or depth.A straight line is one-dimensional.
2. (figuratively) Lacking depth or believability; flat.
• 1972, Hardie Albright, Stage direction in transitionSuch one-dimensional characters have always existed in the theatre along with more recognizably human characters.
• 1999, Kimberly Kimbell-Lopez, Connecting with traditional literatureIn contrast to this are the flat, one-dimensional characters found in fables.