(this is just my theory so)
So I was just wanting to listen to some music, wanted to listen to some Willow Smith right
Honestly I don't know if some of you know this but...
2 of her songs from album ARDIPITHECUS, have dedication to Marceline/ot
Let me give you some lyrics.
"It's raining knives like all the time" (referring to that scene from Finn and Jake using their imagination in that one episode)
"We're so flying high, catch a ride on Lady Unicorn"
"Marceline, I know your not real in this dimension"
"What's up with your dad in the nightosphere?"
"You touch my hair, I'm playing on your bass"
That's pretty much all the lyrics from the songs name "Marceline" relating to Adventure Time.
btw here's the song. https://open.spotify.com/track/0RCpze7hmowZIGUJs9Dm7w