Tomcat is a
J2EE server. And like all J2EE servers "putting a file under a directory in Tomcat webapps" does not qualify.
Tomcat is not some kind of file server or receptacle for miscellaneous trash. It is a
webapp server. If you want Tomcat to serve up content, it
must be in the form of a webapp - specifically a WAR.
A WAR in strict J2EE terms is a ZIP-format (JAR) file containing certain "files" and "directories". If those components are not present, Tomcat won't recognize file as a WAR and therefore it won't recognize it as a webapp.
What causes confusion is that one of the many ways that Tomcat allows you to deploy WARs is in "exploded" form. An exploded WAR is a WAR that has been unzipped into actual directories and files, contained under a single directory, which is the name of the WAR. Which, by default, Tomcat will use as the webapp's context path root.
In other words, you can do a sloppy simple deployment of a webapp by unzipping a WAR into a directory under TOMCAT_HOME/webapps. But if it doesn't contain the basic elements of a WAR (webapp), Tomcat is likely to ignore it.