It those days, and indeed in all photography on film or on glass "plates", the usual rendering from the camera was a "negative", in which all the tones of the scene were reversed - the sky looks dark, and shadow areas look light. The negative can then be printed to make a normal print (photograph) as many times as you want, on many different occasions if needed.
You could print the negatives at home, using a "darkroom", but most people took the negs to a photo retailer, or to Walmart etc, so that the laboratory could make the prints.
Quite possibly your older relatives have negatives in their possession which you could look at. Colour negatives have all the colours reversed also, and a strong overall orange tone for technical reasons.