MILWAUKEE—Thousands of fans lined downtown Milwaukee streets on Thursday to catch a glimpse of their beloved Bucks in a parade to celebrate the city’s first NBA championship in half a century. Six police officers on horseback clopped past cheering fans at the head of a procession that included a hook-and-ladder fire truck, occasionally blaring its horn, and open-air buses and flatbed trucks carrying Bucks stars including Finals MVP Giannis Antetokounmpo and Jrue Holiday, as well as the trophy they captured Tuesday night with a Game 6 victory over Phoenix. Fans could be heard chanting, “Bucks in 6,” an odd but popular rallying cry with roots in a former Bucks player’s fruitless prediction in 2013 that the team would take down the playoffs’ top seed at the time. Antetokounmpo held his son, 1-year-old Liam, atop a bus as fans along the route chanted “MVP!” Later, he shot a basketball into the …