Jem Aswad Senior Music EditorHolly Humberstone is a 20-year-old British singer-songwriter whose reputation precedes her via several singles released earlier this year — which have garnered rave reviews, ranging from the New York Times to the BBC to the Lefsetz Letter — and a European tour opening for Lewis Capaldi just before the pandemic, during which she played to 12,000 people at London’s Wembley Arena.As is often the case with such seemingly wide-ranging appeal, it’s all for a good reason: