The 5th photo is the only one that doesn't look immediately like a cutout. It's believed to have been the result of a double exposure, but one of the women maintained until her death that the 5th photo was genuine.
The photos: https://www.sothebys.com/en/buy/auction/2020/english-literat...
The dumb thing is believing fairies exist at all. If I see "convincing" evidence of fairies, with today's technology, I would still remain skeptical. It would take a lot more for me to even begin to wonder. Because fairies don't exist, we know where they come from in folklore and literature, and there's so much evidence they don't exist (along with unicorns, the Yeti, gremlins, etc) that a couple of convincing photographs or videos is simply not enough.
Conan Doyle wouldn't have been fooled had he been a skeptical, inquiring mind. Alas! He was just gullible.
Famously, Conan Doyle had Sherlock claim:
> When you have eliminated the impossible, whatever remains, however improbable, must be the truth.
Unfortunately Doyle, because he so wanted to believe, didn't really eliminate the impossible. He carelessly dismissed the most obvious option: that the two girls were playing him for a fool.
Doyle was not a scientist but he admired scientists, discoverers of truths and he desired to be one. He also desired that other people should believe him, that would give him great power.
Think about all those conspiracy theories floating in US today, why do people spread them? It's a Ponzi-scheme, the originators of a conspiracy get great power by having many followers who believe them.
The other side of it is that of course people want to believe great stories that might prove to them afterlife will be better than the current one. JFK is still alive, anybody?
Fairies Wear Boots - Black Sabbath
Could something like flat earth theory have started like this? A bad joke that people believed and it got hyped not because it is true but because idiots believing it is kind of fun.
Back then? Flat earth made all the sense in the world, according to the empirical observations possible at the time. Only it wasn't able to explain some phenomena (e.g ships "sinking" over the horizon), and so evidence accumulated against it, eventually.
[1] https://en.m.wikipedia.org/wiki/Cottingley_Fairies