WEB-INF is a special folder and it and its contents cannot be accessed via a URL.
The reason you could put your welcome page under WEB-INF, is that the welcome page element applies to a resource path (directory/filename), and not a URL. Although URL and filename paths look confusingly alike, they very definitely are not the same thing, so different rules apply.
The only way to put JSP files under WEB-INF and get them served would be if some intermediary software could be persuaded to respond to a URL and access the JSP for you. For example, I put my
JSF page templates under WEB-INF/layout and the Facelets processor reads and processes them.
BTW, we have a
JSF forum and a
JSP forum. This is the JSF forum, but your question is really more of a JSP question. You'll get better/more answers when you post to the right forum.