Railsでスライド機能を実装したいです。。。

前提・実現したいこと

railsで複数画像表示機能をslickを使って実装したいのですが、
スライドになりません。どの箇所を改善すればよろしいでしょうか。。。
初歩的な質問ですいません。

発生している問題・エラーメッセージ

Uncaught ReferenceError: $ is not defined
    at Object../app/javascript/packs/application.js (application.js:16)

該当のソースコード

erb
1  <head>
2    <%= csrf_meta_tags %>
3    <%= csp_meta_tag %>
4    <link rel="stylesheet" type="text/css" href="http://yui.yahooapis.com/3.18.1/build/cssreset/cssreset-min.css">
5    <%= stylesheet_link_tag 'application', media: 'all', 'data-turbolinks-track': 'reload' %>
6
7    <%= javascript_pack_tag 'application', 'data-turbolinks-track': 'reload' %>
8
9    <link rel="stylesheet" type="text/css" href="https://cdn.jsdelivr.net/npm/slick-carousel@1.8.1/slick/slick.css"/>
10    <link rel="stylesheet" type="text/css" href="https://cdn.jsdelivr.net/npm/slick-carousel@1.8.1/slick/slick-theme.css"/>
11
12    <script src="https://code.jquery.com/jquery-3.3.1.min.js" integrity="sha256-FgpCb/KJQlLNfOu91ta32o/NMZxltwRo8QtmkMRdAu8=" crossorigin="anonymous"></script>
13    <link href="https://use.fontawesome.com/releases/v5.6.1/css/all.css" rel="stylesheet">
14  </head>

css
1/*
2 * This is a manifest file that'll be compiled into application.css, which will include all the files
3 * listed below.
4 *
5 * Any CSS and SCSS file within this directory, lib/assets/stylesheets, or any plugin's
6 * vendor/assets/stylesheets directory can be referenced here using a relative path.
7 *
8 * You're free to add application-wide styles to this file and they'll appear at the bottom of the
9 * compiled file so the styles you add here take precedence over styles defined in any other CSS/SCSS
10 * files in this directory. Styles in this file should be added after the last require_* statement.
11 * It is generally better to create a new file per style scope.
12 *
13 *= require_tree .
14 *= require_self
15 */
16
17  @import "slick-theme"; 
18  @import "slick";
19

js
1//= require jquery
2//= require jquery_ujs
3require("@rails/ujs").start()
4//require("turbolinks").start()
5require("@rails/activestorage").start()
6require("channels")
7require('../preview')
8require('jquery')
9/*global $*/
10
11$(function() {
12  $('.show-images').slick({
13      dots: true,
14  });
15});

html
1<div class ="show-images">
2  <% post.images.each do |image| %>
3    <li class="slider"><%= image_tag image.variant(resize: '300x300') , class: 'post-image' %></li>
4  <% end %>
5</div>
6