chords or melodies

hii i've had my keytar for about a year and ive felt stagnant in actually playing it. i have no issue learning piano and have been the past year but im not sure what to do on the keytar because of the one handed restriction. do people normally play melodies or chords, or does it switch and if so when in songs? i'm interested in making music too so knowing what's more important is also vital, thank you!!

i have a shs-200 if that helps, pressure sensitivity is shot