As a key figure in the modernization of Bengali literature, Rabindranath Tagore wrote in every literary form that existed at the time: poetry, drama, prose, memoir, philosophy, musical lyrics. But he didn't write in every form all of the time, and the vast majority of his short stories were written at the end of the 19th century. As the introduction to this Penguin collection of Tagore's stories states, the vast majority of Tagore's short stories were written in the 1890s, and this collection almost exclusively focuses on short fiction from that period.
Tagore wrote short fiction during this period mainly because that's what there was a demand for at the time. Readers of Bengali fiction at the time first and foremost read Bengali-language literature publications. It wasn't an uncommon practice for Bengali writers to serialize novels in these periodicals, much like Charles Dickens would serialize his novels in the British literary press.
Given the demands of his readership, Tagore embraced the short story form, and these works bear many of his hallmarks. Their subject matter is concerned with everyday lives of all sorts of people, and there's equal attention and reverence paid to characters from all works of life. As was the case in his political beliefs and religious practice, Tagore's stories valued individual humans themselves over the class or caste distinctions that might define them, and the sympathy or antipathy he generates for his characters has to do with the character's own ethical merits or peculiarities—not any sort of class or ethnic identity.
Tagore's stories, while focused on a wide swath of characters, do tend to employ a few common tropes and themes. We see a number of tribulations caused by the need to acquire a bridal dowry, as well as the evolving discussion of male and female domestic roles within a marriage. There are also a number of supernatural tales with run the gamut from all-out ghost stories to otherwise realist shorts that touch on superstition.