Kodi assumes that you will define "sources" and then "Set content" for the source to e.g. "Movies" and then scan (scrape) the source, i.e. when it finds a movie it will lookup the movie in TVDB.com and download metadata and fanart etc. to create a rich library view. This fails since you are offline.
To prevent this and still use Libraries you will need to change the scraper for each source to "Use local content only" and provide the metadata via .info or .xml files and locally stored images (in the same folder as the movie normally). The Kodi wiki has lots of info on files/formats and how to arrange the media in folders etc. to do this.
To prevent this and not use Libraries at all .. define sources and browse them via the "Videos" menu item which is a non-Library raw view of the files in the source. Kodi will create thumbnails from the local media, but there's no online lookups.
It sounds like you're missing the step to change the scraper - for each source you've defined.