The easiest way to put images into your new Google Site is to drag and drop your image directly onto the new Google Sites page
Images can be cropped, uncropped or hyperlinked using the image editor
Text over image - insert image as background of a text box.
Image cannot be repositioned or resized. but the text box can be.
This image was made using the animation feature in Google Photos.
Create your animation in Google Photos and upload the animation to your Drive. Make sure you have made the animation public.