Multiupload widget - create more items inside single node
You can try out the Plup Upload module https://www.drupal.org/project/plup which gives a Plup upload widget for images where you can upload multiple images at once to a content.

You can follow the tutorial here:
https://www.ostraining.com/blog/drupal/multiple-image-uploads/


NB: To fix the missing thumbnail bug add $conf['image_allow_insecure_derivatives'] = TRUE; to your settings.php