Words Therapy

Writing for me is therapy.  Not this writing, this writing is just me spewing out crap so that I can have posts for my blog so if someone checks this out for info about my book they'll see something.  Of course, this has very little to do with the book.  By the way, it would be easier for me to put actual story related stuff on this blog once I receive feedback.  Ok, it's only been a week so that may be unreasonable, but I"m inpatient, so whatever.
I've decided on a couple of different premises for another book.  I just feel like writing so I'm just going to decide and go forward with it.  I've said that I don't want to just blog and promote without actually writing, so I'm going to keep up with that.  The problem is that all of the good ideas seem to have been taken.  I had a great idea for something and then was able to rattle off 3 other books or movies that have already done something too similar.  I have another idea that is close to some other ones, but different enough that it should be ok, but I don't have it all thought out.
Here is my question for you...do you expect every idea to be original?

I've created this world and these characters and they aren't fully original.  You could accuse Mitosis or just being like Multiple Man or Mirror Man, but he's deeper than either of those two characters.  Logix is based off of a lot of different characters I guess, especially Stealth from the Ex-Humans series by Peter Cline.  I'm pretty sure Holy Mammoth is all mine along with Gamer and Powerful Dude.  Pd's powers aren't original, but he is, no doubt about that.  Lady Splendid looks like a combination of Power Girl and Ms. Marvel with some Dazzler and Spider Woman thrown in.  So, what is originality anyways.
My hope is that the story, dialogue and characters overcome any desire the reader may have to just say "Dude this is a total X ripoff!"  I worry about crap like that.
Contrary to what I said in the beginning, this has been pretty enlightening just to type out.  Sure, maybe I'm just convincing myself of stuff, but whatever.  I'd love to know what anyone who reads this thinks.  What is the fine line between totally reworking an idea and having an original take on an idea someone else might have also had?
Let me know if you have any thoughts.  Oh, and if you are reading or have read the book, please ask me questions here or on my Amazon author page or on Goodreads or on the Facebook Page...I don't care, I would just love to have some discussion.