Edit in JSFiddle

(function($) {
  // defaults
  $.fn.fullClip = function(options) {
    var settings = $.extend({
      current: 0,
      images: [],
      transitionTime: 1000,
      wait: 3000,
      static: false
    }, options);

    // preload images
    var i, end;
    for (i = 0, end = settings.images.length; i < end; ++i) {
        new Image().src = settings.images[i];
    }

    // sort out the transitions + specify vendor prefixes
    $('.fullBackground')
      .css('background-image', 'url(' + settings.images[settings.current] + ')')
      .css('-webkit-transition', 'background ' + settings.transitionTime + 's ease-in-out')
      .css('-moz-transition', 'background ' + settings.transitionTime + 'ms ease-in-out')
      .css('-ms-transition', 'background ' + settings.transitionTime + 'ms ease-in-out')
      .css('-o-transition', 'background ' + settings.transitionTime + 'ms ease-in-out')
      .css('transition', 'background ' + settings.transitionTime + 'ms ease-in-out')

    // if only one image, set as static background
    if (settings.static) {
      $(this)
      .css('background-image', 'url(' + settings.images[settings.current] + ')');
      return;
    }

    // change the background image
    (function update() {
      settings.current = (settings.current + 1) % settings.images.length;
        $('.fullBackground').css('background-image', 'url(' + settings.images[settings.current] + ')');
        setTimeout(update, settings.wait);
    }());
}}(jQuery));

$('.fullBackground').fullClip({
      images: ['https://picsum.photos/800/500', 'https://picsum.photos/1000/700', 'https://picsum.photos/900/600'],
      transitionTime: 2000,
      wait: 5000
    });

.fullBackground {
  background-position: center center;
  background-attachment: fixed;
  background-size: cover;
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

.caption {
  font-size: 30pt;
  text-transform: uppercase;
  color: #fff;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

 <section class="container">
    <div class="fullBackground"></div>
    <h2 class="caption">動作テストです！</h2>
  </section>