In answer to your question: yes I believe it is. It may take some changes and a whole lot of good writing but I believe it can be done. Just don't make it a wardrobe that gets them into that world :-D. I think it could be done if you want to work at it
IMHO
The Great Uberslacker
Or to put it another way, do you consider all of those stories to be clones of each other?
Obviously, if these stories are considered clones of each other by virtue of being about [a] child[ren] who travel[s] somehow to a magical place and [perhaps] reluctantly embark[s] on a quest there to save that magical place, then the answer is that any story that shares the stated element must also be considered a clone.
If they are not all clones of each other by virtue of sharing the above stated plot element, then it was obviously possible for someone to write a story that was not a clone of any given one of them by virtue of sharing that element, and thus there is no reason a priori to believe that it has become impossible since any particular one of these stories was written.
In any case, whether you believe that all these stories are clones or not, I would be more concerned with making sure that if I ended up writing a clone of one (or more) of them, it was a clone of, say, C.S. Lewis's stories and not "The Neverending Story"
What is the magical place's essence?
What is the hero's character?
What is the danger?
Why is a foreign child more able to save the place than a local adult (or local child)?
Any of these can be ignored or patched with a cliche, but the more of these that you provide interesting, original answers to, the more interesting and original the story will be.
And to answer the earlier question, yes I sorta consider those books/movies I mentioned to be kinda similar, I am just afraid of people saying. "Oh so this is just like _______" like they did when I told them about my last story idea which was about a guy who got to relive the worst week of his life due to a magical airline ticket and everyone was like "its just like groundhogs day!" and I was like ughhh! no it isnt! And as a result I never really got started on the last one, I got in the mood to do this story and I was dreading the "oh this is like alice in wonderland!" people....
Thanks for the input
I have read countless novels based on the Arthur legend. They are all about the same basic story. Are they clones? Absolutely not! And I love every different version. Kids who like fantasy and time travel will like your book, if it is exciting and the characters interest them.
How many times have I heard someone say "Oh, you liked Harry Potter? Have you read The Golden Compass? Or the Wizard of Earthsea? Or Ender's Game?" Or people say "You liked Lord of the Rings.... have you read [insert really long epic fantasy series name here]?"
If it's a good story, it's only helped by its relationship with other good stories. If it's thinly veiled plagiarism, that's a different story. You don't hear people saying "You liked Star Wars... have you seen Independence Day?"
If it's a worthwhile story in its own right, and it isn't just playing on the conventions of the genre, then it's a good thing when it conjures fond memories of other books the reader has enjoyed.