I must say your art work is far impressive to what i done, the background is amazing and so is the drawings.
I also like the idea of your story as well

it very good idea with the portal thing. I had thought about something those that line before with a story idea and the one that I slowly work on is where everyone out of a group of five kids this was long before the tv series or lbt 11 or 12 and even 10 where the group make a wish that was the same one when seeing a shooting star and some how it came true, at the moment they in the world of land before time meeting the gang of five and some how they each are types of the same group of Littlefoot and his friends. (I guess you already read some of it and get what I am saying lol)
Still back to your art, it fanstically amazing.
as for your story, I think Malte is right, if you try to keep human out of it, most likely make a better story, but there has been some that had human in it that did well for example the yugioh crossover with LBT, both stories I read of that before they disappeared was amazing to read, I enjoyed that.
but in the end it your choice
