What is the oldest cave art ever discovered

Mostly no, and for the Sulawesi sites the answer is simply unknown. No hominin remains have been found at Liang Metanduno, Leang Tedongnge or Leang Karampuang, so nobody can say who made these images. Sulawesi had no Neanderthals. The artists were most likely early Homo sapiens, the only human species known there at that time, but that is an inference from the region rather than a link to a fossil.

Spain is different, and the link is also an inference. At Maltravieso, no bones were found with the hand stencils. The attribution to Neanderthals rests on the dates, since they were the only humans then living in Iberia before Homo sapiens arrived there. Researchers led by Alistair Pike and Dirk Hoffmann, writing in Science in 2018, argued for this, and other archaeologists still debate it. I also need to correct my earlier figure: I believe that 2018 study gave Maltravieso a minimum age of more than 64,000 years, not the 66,700 I wrote. I'm working from memory on that number, so please check it against the paper before you rely on it.

So the short version is that the Sulawesi art has no known maker, and the Spanish stencil is attributed to Neanderthals on circumstantial grounds.

Chauvet is one of the great sites of European cave art, and it's a useful contrast to the Sulawesi stencils. It lies in the Ardèche gorge in southern France. Three cavers, Jean-Marie Chauvet, Éliette Brunel Deschamps and Christian Hillaire, found it on 18 December 1994, after a draft drew cold air through a narrow gap in the cliff. Inside they found more than a thousand drawings and paintings of lions, horses, rhinoceroses, mammoths, bears, owls and other animals.

Several research teams have dated the paintings to the Aurignacian, roughly 30,000 to 37,000 years ago, with the best-known panels around 36,000. That makes them much younger than the Sulawesi hand stencil but still among the oldest known figurative art. A rockfall sealed the entrance thousands of years ago, which kept the floor prints of a young person and of wolves, and the painted walls, largely undisturbed. The cave is closed to the public to protect it. The Caverne du Pont d'Arc, a full-scale replica nearby, opened in 2015 and is the way most visitors see it. Werner Herzog's 2010 film Cave of Forgotten Dreams was filmed inside it with special permission.

If you want to go deeper, the French Ministry of Culture's pages on the cave are a good place to start.

Photos via Wikimedia Commons: Paintings from the Chauvet cave (museum replica).jpg) by HTO, public domain.