Blur / Drop Shadow Effect Vector Adobe Illustrator

I am start to learning adobe illustrator, I want to ask about making drop shadow / gaussian blur of an object in vector ( non bitmap / raster ) type.
I found a file and want to use it for study material, but I confuse how / from where this shadow was made.
I check the layers are only one object. But if I ungroup it the shadow was dissapeared.

Adding and editing a drop shadow with original element hidden

I would like to create a drop shadow of a person, and keep only the shadow, without the original person. When I double click the layer and tweak the drop shadow setting, is there a way to hide the original layer ? I know that once I created the drop shadow, I can put it on an other layer and hide the orignal layer, but then, I am not able to tweak the drop shadow settings from the “layer style” pop up again…