Great puffy globs of white snow are falling. Through this pointillist screen of flecked paint you can see fat little human bodies, huddled with their heads down inside their thick winter clothes, trudging through a village whose roofs are like icing on gingerbread houses. This is, unmistakably, the world of Pieter Bruegel the Elder – a world you can enter as never before in an exhibition at Vienna’s Kunsthistorisches Museum that is like having all-areas access to the world’s wildest carnival. Paintings and drawings from across Europe have come together for this unbelievable blockbuster that lets you wander among seemingly limitless vistas of comedy and horror. I spent three hours there before a guard gently threw me out. I was just getting started.

Bruegel’s art is simply more human and generous that anyone else’s. Rembrandt? Picasso? They’re so self-obsessed. Bruegel paints you and me and everyone. In that snow scene he made in 1563, it takes a while to recognise any narrative or symbolism at all. Only on close inspection can you see, through the falling snowflakes, the visitors abasing themselves before a woman and her baby. This is an Adoration of the Magi. I don’t think there’s any Bruegel painting that more beautifully illustrates what WH Auden wrote of his ironic panoramas of all that is human:

“How, when the aged are reverently, passionately waiting

For the miraculous birth, there must always be

Children who did not especially want it to happen, skating

On a pond at the edge of the wood.”

Trees so real they seem to jut out of the painting … Hunters in the Snow, 1565. Photograph: KHM-Museumsverband

And there they are, the skating children, and grownups, too, on blue rectangles of ice from which the snow has been dusted away in Hunters in the Snow, which hangs nearby in the grand galleries of this museum. More children jump, skip and balance on barrels in his epic street scene Children’s Games. Next to that, a town square goes crazy as masked revellers, a woman frying pancakes and hosts of paupers, actors and nuns throng around the jousting figures of Carnival and Lent. Carnival is a fat man sitting on a beer barrel with a skewer laden with roasted meat for a lance. Thin, grey-faced Lent has a long wooden spade with meagre fish on it.

Wherever you look in Bruegel’s art, another human marvel hits you. His paintings are worlds. Each one is abundant enough to look at for hours, and keep coming back to all your life. This is not an exhibition of some old master remote in time. Bruegel’s paintings have fascinated the modern world. Here is his sardonic masterpiece of the horrors of war, Dulle Griet, which inspired Bertolt Brecht’s play Mother Courage. Brecht wrote that “the great war painting Dulle Griet” portrays “The Fury defending her pathetic household goods with the sword. The world at the end of its tether.” Seeing this legendary masterpiece in the flesh for the first time, its horror and black humour burn. This war is hell. Peasant women are beating back armoured soldiers while demon pirates dance in the flames of a ravaged city. Through it all, Dulle Griet stalks with sword in hand protecting her sack of swag. Impervious to the nightmare that surrounds her, she thinks only of surviving and getting rich.

Visions grounded in the real world … Two Monkeys, 1562. Photograph: Staatliche Museen zu Berlin, Gemäldegalerie/Christoph Schmidt

That materialism is a fundamental fact of Bruegel’s world. What is happiness? A full belly. In The Peasant Wedding, plump countryfolk gorge on pancakes while men bring more golden rounds of fried batter. They are the better-off: poor people watch from outside the barn door. The same rule of gluttony drives nature, too, according to his print Big Fish Eat Little Fish. A giant fish has been landed from the North Sea, its stomach full of small fry. But how do we know that? A fisherman is slicing it open with a giant knife. Even the biggest fish have predators.

Money also drives the artist, according to the closest thing to a self-portrait by Bruegel that survives. It depicts a keen-eyed artist at work while a myopic fan watches through thick spectacles over his shoulder. Bruegel has no complaints – for as the gullible connoisseur marvels at the painter’s genius he reaches for his coin-stuffed purse.

Did Bruegel just do it all for the money? It’s a down-to-earth view of his profession that fits in with his earthy realism. This great exhibition gets us closer than ever to the grain of Bruegel’s art. It even has a detailed section on how he prepared the wooden panels on which he chose to paint although, by the second half of the 16th century when he worked, canvas was common. Hard oak surfaces help give his paintings their robust solid brightness. Bruegel’s drawings are the key to his art for they are so much more subtle that you might expect. His drawings of landscapes are full of sensitively observed leaves and tree bark, mountain slopes and distant castles. This eye for landscape is essential to his magic. It marks him out from Bosch, who helped inspire his most fantastic scenes. But where Bosch creates a dream world, Bruegel grounds his visions in ours.

Bruegel’s ultimate masterpiece … The Triumph of Death, c1562. Photograph: Museo Nacional del Prado

The winter trees in Hunters in the Snow are so real they seem to jut forward out of the painting. Yet Bruegel’s sense of landscape is not just a matter of detailed observation. To say all human life is in his art is also to say it’s a kind of globe. He came from Flanders, and Hunters in the Snow may seem a quintessentially north European scene – but Flanders is flat. Where did Bruegel find those jagged rocky peaks that stab into the iron sky? They are the Alps. He was a well-travelled man who made a journey – huge for his time – over the Alps into Italy, as far south as Sicily. His painting of the Bay of Naples is here, with Vesuvius belching smoke as sailing ships bounce on green waves.

Bruegel’s paintings create a sprawling diorama of the world. Space unfurls and people proliferate. It is all so satisfying, but wherever you go, whoever you are, there’s only one destination. The Prado in Madrid has lent Bruegel’s Triumph of Death and on this evidence – the fullest anyone is ever likely to see – it is, in every sense, his ultimate masterpiece. People are shoved into giant coffins by armies of skeletons under a diseased sky. A knight draws his sword to fight death off, but the hordes of the lifeless are unrelenting. All must succumb to the bony onslaught. The end is coming, but we can make the best of things with beer, pancakes and the life-giving genius of Bruegel.

• Bruegel is at the Kunsthistorisches Museum, Vienna, from 2 October to 13 January.