[рони]

yaparoff, делегирование!

usersList.addEventListener("click", function(event) {
    var target = event.target;
    while (target != usersList) {
        if (target.classList.contains("user")) {
            target.querySelector(".user__info").classList.toggle("visible");
            break
        }
        target = target.parentNode
    }
});

css только для примера

.user__info.visible {
  visibility: visible;
  left: 0;
 }