Semplicemente perchè non le hai modificate come ti ho detto.
Questo è il tuo web.xml, e come puoi vedere gli stai dicendo che la welcome page è una jsf, e non una jsp:
codice:
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>*.jsf</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
   
    <welcome-file-list>
        <welcome-file>welcomeJSF.jsf</welcome-file>
    </welcome-file-list>

</web-app>
Cambia la welcome file in
codice:
<welcome-file-list>
        <welcome-file>welcomeJSF.jsp</welcome-file>
    </welcome-file-list>
La pagina welcome... non deve contenere tag jsf come stai facendo tu (<f:view>)
codice:
<%@page contentType="text/html" pageEncoding="UTF-8"%>

<%@taglib prefix="f" uri="http://java.sun.com/jsf/core"%>
<%@taglib prefix="h" uri="http://java.sun.com/jsf/html"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
    "http://www.w3.org/TR/html4/loose.dtd">

<%--
    This file is an entry point for JavaServer Faces application.
--%>
<f:view>
            <jsp:forward page="inputnumber.jsf" />
</f:view>
Cambiala in questo modo:
codice:
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
    "http://www.w3.org/TR/html4/loose.dtd">
<html>
<body>
            <jsp:forward page="inputnumber.jsf" />
</body>
</html>