Youre right, those photos were taken as authentic at the time. I often wonder if people then had a different sense of evidence than we do today. Perhaps we are more sceptical generally, but then I think about all of our modern conceits which require us to believe in things just as ridiculous as fairys.
Life was quite different and we shouldn't judge people, who lived long ago, by the same standards; though many STILL fall for HOAXES today!
GLOBAL WARMING/CLIMATE CHANGE has many "true believers", though, of course, that's all just so much hooey; for example.