Kodi accesses media from "sources" and sources can be configured with different scraper settings. So you can have a source for commercial movies that uses the established conventions for filenames and online scraping and works with the TMDB scraper, and a separate source that uses the "local" file scraper only; that can reference local .nfo files and artwork created for each movie.
If you want personal movies to appear in a library view, the movie must be scraped to the library and that means the local file scraper requires a local .nfo file to scrape content from. Kodi itself will not auto-generate .nfo files but LE being Linux and thus scriptable (and with cron if the script needs to run repeatedly) it's not hard to script and automate creation of a basic .nfo files with minimal content. If there is no matching artwork for the local movie Kodi will grab a frame and show it, though the results can be a bit random.
The alternative is to access personal movies from the "Videos" menu. If you are accessing a source that has also been scraped to the Library Kodi shows the Library content overlaid, but otherwise it's just a raw view of files in folders and Kodi shows the filenames and a frame that has been extracted from the media file. This seems to be what you're looking for?