Have a very simple one for you today. You can change the loading spinner with Gifs from Best Loading Spinner GIFs | Gfycat.
Just copy and paste this into your CSS and your good to go.
#kn-loading-spinner {
z-index: 3001;
background: url(https://thumbs.gfycat.com/ConventionalOblongFairybluebird-max-1mb.gif) no-repeat center center;
background-size: 200px;
margin-top: 3%;
width: 150%;
height: 150%;
}