A faulty SD card reader and interruption of the transferring process could make the photos stored on the SD card turns to be executable and corrupted. You can change to another working SD card reader, try to open the executable files on your Mac, and recover SD card photos with professional recovery software.
It is abnormal when you connect the SD card to Mac and find your photos turn into Unix executable files, it should be presented with the right filename extensions such as .jepg. If you think the defective SD card reader is the culprit, you can try another healthy SD card reader or directly connect it to your Mac via the SD card slot on your Mac.
If those SD card photos are also shown as executable files after switching the SD card reader, you can try to open it with the Open menu of TextEdit, a macOS built-in word editing processor, or type the file name preceded by "./" in Terminal, then press Return.
Not all Unix executable files are supported on the macOS running on your Mac. And it seems that your SD card photos are corrupted due to the interruption when transferring files. If so, you can try some SD card recovery software to recover your damaged photos, and iBoysoft Data Recovery is highly recommended.
You can freely download iBoysoft Data Recovery on your Mac, and freely scan and preview the deleted, lost, corrupted files on the SD card, including your photos, then save the recoverable photos you want to a different location. It's professional and secure, just give it a shot now!