Stricken with self-doubt, paranoia and existential despair, the writings of Franz Kafka have taken generations of readers on what the author called “the descent into the cold abyss of oneself”.

A trove of 150 drawings, retrieved from a Swiss bank vault in 2019 after years of legal wrangling and presented to the public for the first time on Thursday, offers a more cheerful interpretation of the term “Kafkaesque”, however.

Populated by long-limbed clowns doing silly walks, Chaplin-like men with bowler hats, and slapstick horse-riding accidents, the previously unseen sketches and doodles showcase a man with a sunny imagination.

“It’s hard to imagine the saint-like being who created these weightless drawings as an unhappy man,” wrote the German novelist Daniel Kehlmann in an essay for Die Zeit newspaper.

Far from mere doodles, the drawings also show Kafka to have been a man of considerable draftsmanship and artistic ambition. “We discovered that Kafka used to engage intensely with visual art,” said Andreas Kilcher, the editor of a book of the Kafka drawings, published by CH Beck in Germany on 2 November and by Yale University Press in the US and UK next spring.

“His peers at school and at university had an immense interest in art, which Kafka not only shared but practised with real vigour”, said Kilcher. “It was certainly more than something marginal to him.”

Kafka, who grew up in German-speaking Bohemia, now part of the Czech Republic, studied law at university in Prague from 1901 to 1906. So serious was his interest in art, said Kilcher, that an admiring fellow student who would later guarantee Kafka’s posthumous fame initially only knew him as an illustrator.

His friend and eventual executor, Max Brod, used to pick what Kafka used to dismiss as his “scribblings” from waste-paper baskets or cut them from the margins of legal text books. When a tuberculosis-stricken Kafka instructed Brod to burn his manuscripts unread after his demise, he explicitly mentioned these drawings.

After Kafka’s death in 1924, Brod ignored his old friend’s plea and published the novels, short stories and diaries to growing critical acclaim. A selection of 40 drawings was also made public, which emphasised the gloomier side of the writing: since the 1950s, novels like Metamorphosis and The Trial have often been illustrated with stickmen in a seeming state of existential despair. The rest would remain hidden from the public for decades.

Fleeing Czechoslovakia after the Nazi invasion in 1939, Brod took Kafka’s writings and drawings with him into Palestinian exile. Before his death in 1968, he gave the papers to his secretary, Esther Hoffe, with instructions to give them to the “Hebrew University of Jerusalem, the municipal library in Tel Aviv or another organisation in Israel or abroad”.

That directive too was ignored, and the Hoffe family kept Kafka’s papers locked away in bank safety deposit boxes in Israel and Switzerland until Israel’s supreme court ruled in 2016 that the manuscripts were the property of the National Library of Israel. The contents of the final cache of papers has been publicly accessible via the National Library of Israel’s website since June.

The 52 individual pieces of paper discovered in 2019, including one complete sketch book and several loose cuttings, not only defy Kafka’s reputation as a gloomy and permanently anguished existentialist, they also share a feature with the paintings Kafka described in several of his novels and short stories: inhabited by men riding flying buckets, singing mice and creatures made of household detritus, the dream-like tales often seem to defy the visual imagination of his readers.

In an afterword to the German edition of the drawings, the philosopher Judith Butler notes that Kafka’s creations often become harder to visualise the more detail he describes them in. In the story “The Cares of a Family Man”, the narrator describes a creature that lives in his home, which looks “like a flat star-shaped spool for thread”. The creature, called Odradek, “is described in detail but that description yields no fixed image”, Butler notes in her text. “Readers have sought in vain to draw Odradek, its bits of multicoloured thread, its spool, crossbar, star, and rod.”

“Kafka’s drawings are a far cry from realistic depictions,” said Kilcher. “There’s usually an element of abstraction, and they [are] rarely spatial but always dynamic.”

Kafka could sometimes come across as actively hostile to visual art, objecting to his publisher’s plans to illustrate his short story The Stoker with a woodcut of New York harbour, and begging his editor never to visualise his most famous creation. “The insect is not to be drawn,” he stipulated in a 1915 letter about the cover of Metamorphosis. “It is not even to be seen from a distance.”

For Kilcher, Kafka’s aversion to visual art was not a sign he had ended his artistic ambition. “I don’t think Kafka fell out of love with art as such,” he said. “He respected drawing and writing as two autonomous art forms.”