Using SAPUI5 / OpenUI5

You can load UI5 in any HTML file with the following script (which already contains jQuery): 
<script id="sap-ui-bootstrap"
   src="/resources/sap-ui-core.js"
   data-sap-ui-theme="sap_bluecrystal"
   data-sap-ui-libs="sap.m"></script>

A simple application page could look like this: 

<!DOCTYPE html>  
<html><head>  
    <meta http-equiv='X-UA-Compatible' content='IE=edge' />  
    <title>Hello World</title>  
  
    <script id='sap-ui-bootstrap' 
        src='/resources/sap-ui-core.js'  
        data-sap-ui-theme='sap_bluecrystal'  
        data-sap-ui-libs='sap.m'></script>   
  
<script>  
    var btn = new sap.m.Button({  
        text:'Hello World',  
        press:function(){alert('Hello!')}  
    });  
    btn.placeAt('content');  
</script>

</head>
<body id='content' class='sapUiBody'>
</body>
</html>
If your application requires a UI5 library not deployed on this server, but deployed at a different location, that library can be loaded as follows (the example loads it from a folder relative to the application HTML page): 
sap.ui.getCore().loadLibrary("sample.uilib", "resources/sample/uilib");
var oExample = new sample.uilib.Example({text : "Hello OpenUI5", tooltip : "My Tooltip"});