Final answer:
Richard Wagner's operas are credited with establishing German Romantic Opera, focusing on ordinary people and incorporating nationalism and folklore into the movement of Romanticism in music and the arts.
Step-by-step explanation:
The work that established German Romantic Opera and featured ordinary people as central characters, dealing with their concerns, fears, and loves is most closely associated with the composer Richard Wagner. Wagner's operas often abandon traditional classical forms in favor of a more integrated musical-dramatic structure, which he called "Gesamtkunstwerk" or "total artwork". His works had a significant emphasis on nationalism and were inspired by German mythology and folklore, reflecting the Romantic movement's infatuation with the natural and simple life as well as the traditional and mystical aspects of German culture.
During this era, Romantic music was characterized by the expression of intense human emotions, ranging from anger and passion to joy. Performance art forms such as Ballet and Opera developed during this time and were built on the evolution of classical music and stylized dance, incorporating dramatic storytelling and popular art forms, and ultimately influencing contemporary performance styles.
The Romanticism movement itself was a reaction against the structured thought of the Enlightenment, with Romantic artists and composers pushing the boundaries of expression, seeking inspiration from love, nature, myths, legends, and the deep-seated emotionality of human existence.