The objective of this paper is to structure the role of the human in metal machining by organising operator participation into three functional roles and analysing their evolution across increasing levels of automation. Using drilling operations as a representative case study, the research integrates the Human-centric Manufacturing Model with the ISA-95 architecture to compare human involvement in classical, automated and autonomous production environments. The results indicate a systematic shift of human contribution from direct physical execution toward supervisory, cognitive and organisational functions. Advances in machine learning, digital twins and multi-sensor monitoring - together with increasing material complexity such as composite stacks and additively manufactured components - transform machining into a data-driven process requiring human validation and interpretation rather than manual intervention. Consequently, boundary physical roles diminish, while cognitive-augmented and analytical-organisational roles become central to planning, monitoring and governance of autonomous systems. The findings show that increasing autonomy does not eliminate the human from manufacturing but redefines the operator as a supervisor, interpreter and orchestrator of cyber-physical production systems, supporting safety, reliability and continuous improvement in Industry 5.0 environments.