The earliest music I pretty much memorized from my first hearing was off the radio. But lots of it was from the old television serials. For me, some of the best music was the background music for the Lone Ranger. That series has been rerun many times over the years. Episodes were run during many of the local TV station Saturday "kiddie shows" back in the day.
Here's the cut from the Lone Ranger that has haunted me ever since I first heard it. I wish I knew who wrote it.
More of this piece is played in other episodes, but this is the most of it I could find right now.
The music from the Lone Ranger got used over and over, from one episode to another. It gets so familiar that after a while you realize the music is often a hint as to what's about to happen in the episode.
There are a lot of good lessons in this "old" music.