I think people here have different definitions on what they mean when they say a job has 'depth', so really, the question I have is, what counts as 'depth'? What quantifies one job having more 'depth' than another?

There is also the flexibility, is that separate to 'depth' or is it a component of 'depth'?

Once this baseline has been established, a proper discussion can be had comparing different jobs because, at the moment, it is going nowhere.