How new is "new phone"? Maybe OP bought a second hand phone, and all these images have been left behind in the "Whatsapp Images" directory. Especially if it's pictures of local people, I would guess someone local sold this phone to the store and it didn't get wiped properly.
I've actually bought a new phone once and it had someone's list of phone numbers. It still looked pretty new, so I guess someone bought it, used it for a week or two and returned it. I was just annoyed at the scummy seller...
A bit longer: OP went to a shop to get his phone repaired. Shop gave him a loaner phone, which had been used by many many people and apparently never wiped. OP set up Google backup on that phone and those photos got uploaded onto his WhatsApp backup. OP got a new phone, set up WhatsApp, and WhatsApp downloaded the pics from the loaner phone onto his.