The base is original from the producer (chords and melodies), but is complemented with elements that complement the song that come from samplepacks, usually, vocal chops, guitars, wobbles sections, glitch effects. It is the standard in which most of producers work, in a project you will find MIDI files made by the producer, but also melodic loops.
The melodies are 100% authentic (except the arpeggio which was sampled), and I dared to experiment with some vaporwave elements mixed with drill drums.
Sample pack Black Octopus Sound - Slap House Essentials
Loop name SHE_Arp_Loop_105_Em_1