Unyielding

An unyielding person refuses to change their opinion, decision, or demands. While this can mean tenacious, unwavering, and firm, it can also imply stubbornness or being unreasonably immovable.

While "resilient" implies the ability to bend, recoil, and bounce back to a previous state, signifies refusing to move or break, continuing forward without retreating. An unyielding entity does not rebound; it resists impact entirely. Pop Culture & Gaming Context (Fallout 76) Unyielding

It describes materials that are hard, solid, and difficult to break or move, such as "unyielding concrete" or a "hard and unyielding sofa". An unyielding person refuses to change their opinion,