The problem is that you aren’t giving Plex enough information to identify your music. Whatever information it has is telling Plex that you’ve got a bunch of music from different artists, and they appear (to Plex) to be in a single album, so it’s not surprising that “Various Artists” is the best it can do.
Plex essentially has two possible ways to identify your music - either by the folder/filename structure, or by accurate embedded tags. I don’t know if Plex supports ID3v1, but upgrading to ID3v2.3 or 2.4 couldn’t hurt.
So you either need to organize your files into folders/filenames according to Plex’s guide, or get the embedded tags in order.
