عدم کارکرد img-gallery

<!DOCTYPE html>
<html lang="fa">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>project12</title>
    <script
      src="https://kit.fontawesome.com/cac5ba1843.js"
      crossorigin="anonymous"
    ></script>
    <link
      rel="stylesheet"
      href="https://fonts.googleapis.com/css2?family=Material+Symbols+Outlined:opsz,wght,FILL,GRAD@20..48,100..700,0..1,-50..200"
    />
    <link rel="stylesheet" href="/assets/css/style.css" />
    <style>
      .course-title {
        font-weight: bold;
        font-size: 38px;
        color: #faf5f5;
        display: flex;
        justify-content: center;
        align-items: center;
        margin-top: 50px;
      }
      * {
        margin: 0;
        padding: 0;
        box-sizing: border-box;
      }
      body {
        background-color: #cbe56b;
      }
      ul {
        list-style: none;
      }
      .image-gallery {
        max-width: 700px;
        margin: 30px auto;
      }
      .image-gallery img {
        display: block;
        width: 100%;
        height: auto;
        border: 4px solid #efefef;
        box-shadow: 0 3px 4px rgba(0, 0, 0, 0.2);
      }
      .thumbnils {
        /* margin: 0 auto; */
        display: flex;
        justify-content: center;
        align-items: center;
      }
      .thumbnils li {
        margin: 0 10px;
      }
      .thumbnils li a img {
        border: 4px solid #efefef;
        box-shadow: 0 3px 4px rgba(0, 0, 0, 0.2);
        max-width: 120px;
      }
    </style>
  </head>
  <body>
    <p class="course-title">پروژه شماره12</p>
    <div class="image-gallery">
      <img src="assets/img/6.jpg" alt="" />
    </div>
    <ul class="thumbnils">
      <li>
        <a href="assets/img/a2.jpg"><img src="assets/img/a2.jpg" alt="" /></a>
      </li>
      <li>
        <a href="assets/img/a3.jpg"><img src="assets/img/a3.jpg" alt="" /></a>
      </li>
      <li>
        <a href="assets/img/desk.jpg"
          ><img src="assets/img/desk.jpg" alt=""
        /></a>
      </li>
      <li>
        <a href="assets/img/4.jpg"><img src="assets/img/4.jpg" alt="" /></a>
      </li>
      <li>
        <a href="assets/img/6.jpg"><img src="assets/img/6.jpg" alt="" /></a>
      </li>
    </ul>
    <script
      src="https://code.jquery.com/jquery-3.7.1.js"
      integrity="sha256-eKhayi8LEQwp4NKxN+CfCh+3qOVUtJn3QNZ0TciWLP4="
      crossorigin="anonymous"
    ></script>
    <script>
        $(document).ready(function () {
        $(".thumbnils a").click(function (e) {
          e.preventDefault();
          $("image-gallery img").attr("src", $(this).attr('href'));
        })
      });
    </script>
  </body>
</html>