There are many parts, aspects, dimensions of music. Pitch, rhythm, dynamics, timbre are the starting points, then as further differentiations we could add harmonic complexity, both vertical and horizontal, melody, range, lyrics, articulations, rhymes (or not), emotional implications (calm/frenetic, elegance/base), speed, contrast in each of these areas or none, etc., the list goes on and on. It's interesting that much music that we think of as challenging is actually only complicated in one or two dimensions. For all the pyrotechnics of Funk or Metal, and the excitement of groups like Yes or a Brad Paisley guitar solo (for that matter, absolute music from the Classical era <1750-1825>) - most of what's going on is melodic and many of the other dimensions are untapped (and just because it's hard to play or sing doesn't mean it's complex musically). This is not a negative comment on these styles or songs; rather it's an indication how easy it is to make great, fun music - and that's also very interesting. You'd think all great music would have to be really complicated and use each of 15 dimensions well. But great musicians are constantly flummoxed by songs succeeding that are pretty loser musically (and of course, lots of professional musicians look down now on the music they loved as teenagers). But what's really going on is that great music is like filling up a bucket: you may not have great lyrics or a good hook, not very exciting chords, but if enough other things in the song ARE good you get a total that makes the music succeed. The bucket fills up, but with uneven parts. Next time: What do most people want in their music?
Practice requires diligence, but don't equate practice with faithfulness. Practice doesn't make you a better person, just a better musician.