Final answer:
Pierre-Auguste Renoir is the impressionist artist who painted 'Le Moulin de la Galette', a lively scene of an open-air dance hall capturing the essence of Impressionist painting by depicting the working class enjoying their Sundays.
Step-by-step explanation:
The impressionist painter who created 'Le Moulin de la Galette', which shows ordinary people enjoying themselves in an open-air dance hall, is none other than Pierre-Auguste Renoir. Renoir's work is emblematic of the Impressionist movement which aimed to capture the beauty and dynamism of ordinary life with a vivid play of light and color. His fondness for depicting the social interactions of the working class, capturing lively scenes with fluid brushstrokes and dappled sunlight effects, is particularly evident in this painting.
'Le Moulin de la Galette' depicts a leisurely Sunday afternoon in Montmartre, a bustling area known for its cafes and dancehalls frequented by the working class. Renoir is known for his mastery in the application of brushstrokes that create the illusion of light and shadows dancing across the scene, thus making this one of the best examples of Impressionist painting. This work of art, along with many others by Renoir, was able to break away from traditional academic standards and gain acceptance into the Salon, thereby propelling his credibility as an impactful artist.