Tschabalala Self is strikingly upbeat and determinedly hopeful. The American artist is preparing for the unveiling of Lady in Blue, her new work for the fourth plinth in London’s Trafalgar Square: a monumental, vividly painted bronze figure of a black woman moving confidently into the future. Self speaks with certainty about the sculpture, despite the experience she had with her previous public artwork in Britain. “Yes,” she says from her home in upstate New York. “That was an openly racist act.”

In 2022, Self presented Seated at Coal Drops Yard in King’s Cross. Like Lady in Blue, it was a large painted bronze sculpture of a black woman, though this figure sat quietly in a chair. The work was displayed in King’s Cross without trouble before moving to the De La Warr Pavilion in Bexhill-on-Sea, where it met a harsher response. “During the first week,” Self says, “someone spray-painted it white, specifically over the sculpture’s skin.” The gesture was unmistakably racist. “My first reaction was pain that the sculpture had been damaged. Someone had committed violence against an object that I had made with care and love.”

The Pavilion considered arranging a protest after the attack, but Self instead suggested a community cleaning event. “It seemed like it would be more healing, because so many people were horrified by what had happened.” Hundreds of people came to help, and the paint was completely removed by the end of the day. Conservation specialists were no longer needed. “It was not the first time I had encountered racism,” Self says, “but it was the first time one of my sculptures had been vandalised.”

Born in Harlem in 1990, Self has developed a highly recognisable visual language built from collage, pop-inflected figuration and social idealism. It has made her one of the most prominent younger artists working today. Her work is held by major institutions including MoMA, the Guggenheim and the Whitney Museum in New York, as well as the Albertina Museum in Vienna. She has exhibited at the Hammer Museum in Los Angeles and the ICA in Boston, and works with leading commercial galleries. Her art is loud, saturated, playful and celebratory: an exuberant tribute to ordinary bodies and everyday lives. In spirit, she recalls a contemporary New York counterpart to the French artist Niki de Saint Phalle, known for her joyous sculptural figures.

“The core message in my work is that everyone should feel present in their own body,” she says. “People should feel secure, comfortable and empowered in their physical selves. I believe that is a human right. My work is about helping people recognise that their bodily experience is something to appreciate, and that living physically in the world can be a source of pleasure.”

Self regularly returns to these ideas, speaking with optimism and conviction about bodies, confidence and what she calls “vessels”. “Simply being a person,” she says, “is an expression of dignity. It takes courage to exist as a human being. That is something worth honouring.”

Her straightforward, affirming outlook can appear unusual beside the more severe, intellectual and politically charged projects that have occupied the fourth plinth in recent years. How will Lady in Blue relate to Teresa Margolles’s installation of life-masks from hundreds of transgender and non-binary people, which it replaces? Or to Samson Kambalu’s forceful anti-colonial monument to the Pan-African preacher John Chilembwe in 2022? Compared with these works, Self’s sculpture may look disarmingly accessible and cheerful. Where is the rage, the confrontation or the dense conceptual framework often associated with contemporary public art?

For Self, however, the combination of joy and clarity is precisely what makes the work radical. “Imagine you are a designer,” she says. “Making something simple that also works well is considered the highest level of conceptual discipline. Yet in fine art, simplicity is often treated as if it means there is no conceptual depth.”

Self rejects that assumption, choosing readability over obscurity. “If an artwork cannot affect a broad group of people across different educational, economic and racial backgrounds, and affect them in a broadly shared way, I would see that as a limitation of the artist rather than of the audience. If art is powerful enough, it should be understandable, at least in part, to anyone who encounters it. That is part of what makes an artist great.”

Discussion of Self’s art often centres on its celebration of black bodies. Does she think that description narrows the scope of what she is trying to do? “It is too simple, and it can be restrictive. The work is frequently discussed in those terms, but that is only a surface reading. The figures are black because they reflect my own physical experience. But they are intended to speak to human experience beyond racial identity.”

Self wants viewers to see Lady in Blue as an everyday presence. For decades, audiences have accepted Antony Gormley’s use of his own body as a symbol of humanity more generally. But, Self argues, some people still struggle with the idea of a black woman representing an ordinary universal figure. “For many people, that is still a significant intellectual leap,” she says. “One of my first intentions was to show the figure as a woman. If someone cannot immediately identify with her because she is black, that reflects a wider social condition that needs to be examined.”

Some of that examination followed the attack on her work at the De La Warr Pavilion, though the incident could understandably remain in the background as she approaches this new commission. The fourth plinth is not positioned outside a gallery in a quiet coastal town. It stands at the heart of one of London’s most visible public spaces, attracting enormous crowds and countless opinions. Does that concern her?

“I am prepared for every kind of response. I am not anxious, because everyone has a right to their own opinion about the sculpture. Each reaction will reveal something about the reality we are all living in now.”

She sounds sincere, though she would hardly be blamed for worrying about negative reactions after the earlier vandalism. “The point is not for the artwork to be liked,” she says. “It is not even for it to be loved. The point is for it to do what it is meant to do. Its purpose is to encourage people to talk, to question beliefs they have carried with them, and to create room for different ideas.”

One thing is clear: Lady in Blue is heading somewhere. She is striding, marching and pushing forward, as though nothing can block her path. Self says the figure moves towards a shared future while refusing the burden of history contained in Trafalgar Square’s monuments and architecture. “It is about making room for everyone in places that have traditionally been weighed down by old gestures, old systems of belief and old impossibilities,” she says. “I did not want to make a work that simply reacted to the past. I wanted to create something like a beacon, something that could illuminate a possible future.”

What might that future look like? “I hope that all of us can have physical, mental and political room to live freely, without our freedom damaging the freedom of someone else.” She laughs, then adds: “I hope that does not sound too American.” It is, I tell her, an extremely American sentiment. “I just want everyone to have the ability to be free,” she says. “Isn’t that what everyone wants?”

Simplicity, pleasure, physical presence and, most of all, freedom: Self’s imagined future appears as bright and vivid as her towering blue figure.

Lady in Blue by Tschabalala Self will be unveiled on 10 September.