Some philosophical objections distinguish motion in general from particular movements. If each particular movement starts, must the entire sequence of movements also have a starting point? That is the issue.
One reply argues that motion-as-a-universal is not an independently existing external entity alongside its instances. A conceptual generality must not be transformed without argument into a separate eternal object.
Still, the distinction between each member beginning and the series having a first member remains. The argument needs to address both rather than treating them as interchangeable.