If you have gone through the demo URL given by my colleague i.e https://demo.theme.co/integrity-1/shortcodes/responsive-lightbox/, you can find that the image class name is the selector name in the lightbox shortcode.
[image class="my-portfolio" src="https://yourdomain.com/image.jpg" alt="Example" type="thumbnail" link="true" href="https://yourdomain.com/image.jpg" title="Example Image"]
[lightbox selector=".my-portfolio" deeplink="true" opacity="0.875" prev_scale="0.75" prev_opacity="0.75" next_scale="0.75" next_opacity="0.75" orientation="horizontal" thumbnails="true"]
In the above example, my-portfolio is the image class which used as selector in lightbox shortcode.
But in your case, the selector is .single-galery img whereas the image class is single-galery, I would suggest you remove the img from the selector and check if the lightbox is working.
Alternatively, you can try using the bundled grid plugin name Essential Grid, which has the features you need. Please visit the links below for more details and plugin usage instructions.
Hope it works for you.