Place Command Does Not Create Smart Objects
When you go to File > Place to bring an image into your document, Photoshop turns it into a Smart Object.
If you would like for the image to remain rasterized, bring up the Preferences panel by pressing Ctrl K (Windows) Command K (macOS), and under the General tab, uncheck “Place or Drag Raster Images as Smart Objects.”
From this point on, Photoshop will no longer convert the images that you place into Smart Objects.