Great work!
Ive already given you my ideas I think, but I'll leave you a written review in case I forgot anything. I agree with benyue - while there is a theme, it it hard to pick it out from all of the other material unless you know what you're looking for. You have loads of wonderful stuff here, but sometimes you need to give the listener a nudge in the direction you want them to be listening :)
Some points of thought:
1. A motif doesn't have to be melodic - you can have an instrument or rhythm-based reoccurring theme. For instance - if you begin a piece with a gripping oboe solo, and then take out the oboe for 50 bars, when it comes back the listener will draw the connection, even if the melody is different.
2. Sometimes when I'm writing music I try to see how many times I can slip in the same motif. Beethoven was an absolute master at this - his 5th symphony is a great example. If nothing else it's a good exercise to try, and will get you thinking about intertwining lines and themes vs stacking them left to right.
Your music has such clarity, and has some clear Elfman influences in places :). Can't wait to hear more collaboration projects!