AWhen the film first came out, it was assumed that the beings seen after David and Teddy have been frozen were aliens. They are actually future mechas that have evolved to their current state and appearance, seeming to fulfill Gigolo Joe's words that when the end came, mechas would still survive after human beings had died out ("They made us too smart, too quick, and too many. We are suffering for the mistakes they made because when the end comes, all that will be left is us."). This becomes obvious when watching the film a second time, since the voice of the chief mecha is the same voice in the beginning - the actor Ben Kingsley.The future mechas, much like human beings, are in a search for information regarding their past, which is why David is such a perfect specimen for them to find, given he lived among humans and his mind is filled with their interactions.
AMeryl Streep provides the voice of Blue Fairy. The credits (and so, the IMDb also) identify her as Blue Mecha, but that's not correct.