The scan provided might have problems due to the resolution of the original scan. This lead to a lot of “floaters”, disconnected polygons which are not connected to the main body. These are an unnecessary load on the computer.
Note the numerous meshes. There are over 300 separate bodies.
In object Mode, select the main body.
Move the body using either object properties or the tool from the bar on the left, this will free the main body from the small floaters.
Select all the small bodies with the cursor.
Push delete on the keyboard to remove them.
Note the number of remaining bodies.