An imported ant svg shape is repeated along an editable free form path. A linked instance of these ants is then added below and assigned a different randomized color to work as a shadow of the ants. The linked instance layer will update with any changes to the original parent layer, so any changes to the ants or the path will also update the offset shadows to they match.
Example using the Path repeater and linking to a second path layer, as well as an introduction to using instance layers to create inheriting copies of layers.
You can also find a video demonstrating how to work with the path repeater and instance copies here: Ant line instance shadows