They are definitely there ! Under Library, the left-hand and should have a list of playlists (like it always did) - if however, it's defaulted to hidden, then hover mouse over the words Music Playlists (when iTunes is in focus) and a show button should appear just to the right of the Music Playlists text. Click on this and your playlists will be there.
The internal Mac iTunes Music Playlists section should be below "Eds iPhone" info (Devices). Try scrolling down to see if it is there (your picture does not show what is below "Eds iPhone"). On my iTunes my Music Playlists are below the Devices section. I have iTunes 12.8 (High Sierra), but maybe you found a problem with Mojave (iTunes 12.9?).