NEW YORK — Peres Jepchirchir made her case as the best marathoner on the planet, while Albert Korir announced his return on the streets of New York City. The Kenyans swept the titles at the 50th running of the marathon, which returned to the five boroughs after a year-long absence because of the pandemic. Jepchirchir, the Olympic gold medalist, became the first athlete to double back from gold at the Games to win New York just over three months later. After a slow start, she hammered the last eight miles under 5:20 pace, outkicking fellow Kenyan Viola Jeptoo in the final half-mile. Her winning…