Faced with an iPad full of images and no copy of iPhoto to help you move those images from iPad to Mac, where do you turn? To another application bundled with the Mac OS that you may have missed.

You should be able to switch to Image Capture on your Mac, import the incompatible files, and then use a conversion tool, like iMazing HEIC Converter (free) for images, which runs on macOS 10.9 ...