Henry Moore at Tate Britain

Henry Moore: less is more. So runs the familiar quip. Coined in the 1960s, when Moore was the most famous sculptor in the world, it referred not only to the scale of his muckle bronzes but their unprecedented ubiquity at a time when every mayor and museum director in the west seemed to think that only a Moore could hit the spot, and our civic spaces were full of reclining figures with holes through their middles that spoke in terms both ancient and modern of our common humanity. As they still are: surely the epigram still fits?

It is a question for the curators of this enormous survey at Tate Britain (until 8 Aug), and not just because they have had to select from almost 11,000 pieces. Moore made far too much to be consistently original. His work became as repetitive as it has become familiar; this tends to neutralise whatever power it may have. All of which presents problems for anyone wishing to make us look at it once again with anything like new eyes.

Looking at it in the first place is hard enough for some. I freely admit to almost total aversion. This is not just a mutiny against the dutiful worship once – still? – occasioned by his art; or the respect for him as heroic war (and postwar) artist; emblem of the greatness of Britain; import-export pioneer, bringing in world art from Aztec carvings to Aegean deities, sending it back out again reworked as English modernism. Nor is it a reaction against his dominance in our culture any more than our landscape.

It is not even that his sculpture is so lacking in beauty or grace. To say that a work is ugly can these days amount to praise, but Moore's sculptures are ugly to no obvious purpose. Lumpy, swollen, etiolated, hunched, extruded, squashed, dismembered: these effects are all part of the lexicon of three-dimensional art, and essential to the work of many great 20th-century sculptors, from Giacometti to Germaine Richier, Louise Bourgeois and David Smith.

But in Moore's hands, it all dwindles without force or focus. His lifelong subjects – the seated, standing or recumbent figure, the king and queen, the mother and child, the head: they all get the same treatment to the point of homogeneity. Is there really no difference in his mind between a snake, a wounded soldier and a baby suckling at the breast?

Take the Tate's own Falling Warrior from 1957, with its terrible knees and its bony flanks and shanks straight out of Dalí. The pinhead is pierced with two sightless holes, the pelvis and abdomen are fused in a shapeless, distended blob. It has a circular shield to invoke classical tradition. Otherwise it might as well be Moore's Draped Seated Woman from later that same year. The only real difference – for there is no shift of character, tone or effect – is that the female edition is fitted out with those conical all-purpose breasts.

This exhibition does Moore no favours by showing multiple versions – as opposed to variations – of the same themes: the carved marble girls from the 1930s, the mothers, the abstract forms strung like blunt and tuneless harps, the monumental reclining women in plaster, bronze or elm. The same but bigger, the same but worked in stone: this presentation gives the lie to all sorts of stock praise about Moore's art, from its sensitivity to scale to its supposed truth to materials.

The artist the curators are hoping to advance is darker, more anxious and disturbing. A leftwinger, a pacifist, a veteran of the first world war, horrified by the second, a partisan of the Spanish republican cause, a founding member of CND, he is also presented as a political radical. This is mainly a matter of biography (though can he really have been a member of the Communist party, as suggested?) until it shades into the interpretation of his work, when it becomes fairly absurd.

Take a sculpture such as Atom Piece. Everyone says it is a hybrid of skull and mushroom cloud, as if it were some satirical duck-hare collage by John Heartfield. But is the skull more bruited than apparent? And what is the political content, if any at all? Moore talked vaguely of seeing the sky anew through its holes; for all its heavy metal mass, the sculpture remains hopelessly vacant.

It is certainly true that Moore was there, in his knitted tie, among the French surrealists. You can walk round the show spotting the influences – Dalí, Picasso, Arp, Picasso again, and again – but then the same is true of every source, from the Mexican rain god Chacmool to Cézanne's late and lugubrious Bathers. And it always seems to come down to form as opposed to content.

The bodies are assembled out of disparate parts – walrus head, Aztec torso, Giacometti extremities – but never with any feeling for affinities, still less significance. I don't doubt that the curators find Moore's figures "abject, erotic, violated, visceral", though I wonder how they can tell. To me they are just mild and meaningless.

Once the influences start accumulating into an inventory, it is all over. There is the clear fact that the originals – a Cycladic head, a Picasso odalisque – will always be so much better than Moore's reprise. Which in turn raises the question of his contribution, whatever is divisible from the sum of borrowings. This ought to be distinctive form: Moore, after all, is a sculptor. But it seems more like the surface itself, a sort of all-over web of containment, elastic as a sheath, seamless as nylon stockings.

The momentous works in this show are – as anyone might expect – the drawings of sleepers sheltering in underground stations during wartime air raids: their bodies, heads and arms united in the undulating rhythms of Moore's pencil, ink and crayon. People as fragile monuments of endurance. When he adds chalk, there is a powerful sense of fog and dust, of gloom stretching away into sepulchral tunnels.

All the grand claims about archetypes, about humanity essentialised in beautiful organic forms: all are justified by the drawings of sleepers, and the rarely shown images of miners at the coal-face. Moore finds form, in all respects it seems, in draughtsmanship rather than sculpture.

Comfortable, passive, smooth, polite: the subject can be as dramatic as a mortally wounded man, as monstrous as a lopped and bloated corpse, and still the sculptures lack singularity and power. What strikes most is their family resemblance, their Mooreishness, their steady continuation down the long decades of his career. It is almost half a century since Herbert Read described them as "forms that are vital to the life of mankind", as if we could scarcely survive without them. The world has changed, but the art has not. I cannot believe we were looking at the same sculptures.