@rinaldop I might be on the wrong track here but are all the images in as good alignment as the two you posted ?
If they are I might try:
Load the images as layers
Make the selection then invert the selection
Use the attached Multiple-Layer-Actions.scm to cut
Trim to size Image -> Crop to content.
Plenty scripts/ plugins to export the layers to individual png files
As a note, The background(s), not wonderful, there are (ghost) image(s) there. Don't know what to do about that
anyway as an animation: https://i.imgur.com/JUHTpny.mp4
If they are I might try:
Load the images as layers
Make the selection then invert the selection
Use the attached Multiple-Layer-Actions.scm to cut
Trim to size Image -> Crop to content.
Plenty scripts/ plugins to export the layers to individual png files
As a note, The background(s), not wonderful, there are (ghost) image(s) there. Don't know what to do about that

anyway as an animation: https://i.imgur.com/JUHTpny.mp4