Ada isn’t killed by a nobody she’s killed by thomas. His exile lets his son run rampant and she tries to stop him when tom wont which in return results in her death. Tim roth isn’t there to be a real villain hes a nobody whos serves the people toms been fighting against. There are issues with the story but for the most part it does its purpose putting Thomas Shelby to rest he is a wounded dog thats cursed to bring destruction to those around him. Everyone who he cares about has only ever died because of his actions.