Starrgrl!!!! Wow, so great to have you back.
Try this out:

Pretty much, just take the rhythm of the ostinato, and replace the notes of that with the notes of what would be the RH chords, emphasizing the top note. Also, I know 8/8 and 16/16 are almost never used due to the preference for syncopation vs. mixed meter, but since the song NEVER deviates from this pattern it's safe to say it's mixed meter.
I originally had it in 8/8, but I'm really preferring 16/16 now. I was just told that it's in 4/4 before by someone on this forum and it made sense at the time (opinions change over time). Yeah, I'll definitely experiment more. So far, your rendition works reaaaally well. My ONLY issue is that, I generally don't like changing the octaves, but this is an arrangement not a transcription sooooo I'll see how that works technically.
You might also want to add dynamics. Set it to mf maybe?
Maybe people who actually know how to arrange a song and play piano can help more 
I KNEW I FORGOT SOMETHING. I play piano and know how to arrangement (not a professional obviously lol), but I appreciate ALL opinions. I say no matter what level you are, it's always good to get feedback.
While I still gotta practice 5 hours a day I have a bit more free time now....