If an image is saved in WhatsApp images and WhatsApp sent images but not on your phone gallery does that mean the image was not taken using the phone.?

Hi everyone. Bit of a strange one here. I have an image, a selfy to be exact, saved in my files under WhatsApp images and also whatsapp sent images. The image saved in the sent folder is just mirrored. But the image does not show up in my phone gallery. Is it to far fetched to presume that the image was sent via WhatsApp and then deleted only to be sent back via WhatsApp? Also the image in WhatsApp images has no details option. Prehaps a deleted conversation?