How much did you alter them? Why not just retrace over them, make them unique, make them yours.
Honestly, if you would like some advice on drawing backgrounds, I strongly recommend trying to redraw Sierra backgrounds. First, start with exact copies, then later start adding things that you like. Your backgrounds aren't all that bad, you need to work on perspective and detail. I think reworking some Sierra drawings can help you with that. I can't draw at all and you saw my backgrounds. It's just a matter of learning the "Sierra Technique".
As far as plot goes, if you want to pick this game back up, but, you're kind of bored with it, take what you have and rebuild a plot around that. At least all of those backgrounds won't go to waste.
good luck,
-junc