What I did was I saved a sketch I made in affinity designer to pictures,I then went to downloads in finder and in the search bar at the top of the window I typed in pictures that's when all these pictures appeared a lot were the logo's of software that was installed on my Mac but there were a lot of photos of people that I had not downloaded and I didn't recognise the people in them.No one else uses my Mac so they couldn't have been down loaded by any one else.