Loading .stl file as an original form(low poly)

Hello, this is Lee.

I got trouble to load some .stl files.

I'm trying to edit for 3d printing but, in some shapes like low poly designs changes to unintended surfaces.

Just like this.

When I open it as a solid, I can edit, but the form it has is totally different from the original low poly shape.

On the other hand, open as a graphic? the form is just as it was, however, I cannot edit a thing.

May the god of solid doesn't give everything;)

By the way, attached the .stl file that I'm practicing.

I hope there's way out.

Best regards.

SolidworksImport export