Not by itself. A first-line supervisor is not managerial merely because of the supervisory duties unless the employees supervised are professional, so a petition built purely on a headcount of operators is exposed. The more durable claim for a terminal role is management of an essential function of the business at a senior level.
Two ways to be a manager, and only one of them is about people
The first route asks whether the person supervises and controls the work of other supervisory, professional or managerial employees, and has authority over hiring, firing and other personnel actions or, where nobody is supervised, over daily operations. If Halina's shift superintendents are themselves supervisors, they support this route and the chart should show it. The second route asks whether she manages an essential function of the organization at a senior level within the organizational hierarchy.
Loading vessels to grade, managing elevator capacity across a harvest, and holding responsibility for throughput commitments are functional responsibilities, not clerical ones. Choosing this route means the petition must identify the function precisely, show that it is essential to the enterprise, and demonstrate that she operates at a senior level rather than performing the function herself alongside the operators.