Using WordPress and ProPhoto there are a number of ways to reorder images that are present posts, pages or galleries.
Reorder ProPhoto gallery images
To reorder images in a pre-existing ProPhoto gallery in “Galleries > All Galleries” simply edit the gallery and select one of the ordering options.
If you need move single or groups of images select them and drag and drop them in place.
Reorder post/page images
Image blocks
If your page features multiple images blocks, you can rearrange them using the up/down arrows that appear when you hover the block or by grabbing the handle and dragging.
You can also drag/drop the images using the handle in between the arrows but that can be a little cumbersome. To reorder this way find it helpful to put my visual editor in full screen mode and get rid of the sidebar.
Gallery blocks
If you have multiple images displayed in a standardWordPress gallery you have drag and drop reordering options. Edit the block and move the images around one by one.
Once the images are in the order you want, click “Update gallery.”