There's nothing wrong with programming/sequencing instead of playing every note yourself. No-one expects a classical composer or an arranger scoring for orchestra or even small ensembles like string quartets - or pop groups for that matter - to be able to play every part they write on the relevant instrument. They write the music and give it to others to play, then sometimes complain the musicians sound nothing like the composer imagines they should.
And when you tell a synth that it's just not making the right sounds and things need to change, unlike humans it has no feelings to get hurt.
What matters is the end result, which you've done very nicely.
The opening chords remind me for some reason of the sort of thing English church organists play at weddings while everyone's waiting for the bride to turn up. :-)