How can you use the word quintessential in a sentence to describe a photograph?
That photograph caught a quintessential moment in our nation's hsitory.
"Quintessential" is an adjective that describes the perfect example of a particular type, The quintessential quarterback would be one who has all of the traits and qualities those who are knowledgeable about football would expect from a quarterback. There are quintessential villains and heroes. It could be that "quintessential" is generally used to describe people, but that may not be necessarily true.
Yes, as long as you use the word to describe another word in the sentence, original is an adjective. For example, in the sentence "This is an original painting by van Gogh." the word "original" is an adjective. If, however you use the word to describe the entire item as in "This is an original.", it is a noun.
The word photograph is a noun, a singular, common, concrete noun; a word for a picture of something that you make with a camera (often shortened to photo), a word for a thing. The word photograph is also a verb: photograph, photographs, photographing, photographed. The noun forms of the verb to photograph are photographer, photography, and the gerund, photographing.