Limitations

One great way to ensure your fictional world has at least one link with reality is to ensure it has limitations and that is characters have limitations too.  An all powerful character who can do anything any time any where in many ways is an uninteresting character.  They'll just use their powers to get out of whatever scrape they've got themselves into (and bear in mind other characters will know they're all powerful so are likely to avoid confrontation).  The characters who use what skills they have got, who struggle to overcome and get there in the end are far more interesting.  Readers are more likely to identify and so sympathize with them. 

Looking at how your world overcomes its limitations (likewise individual characters) will drive your story forward whether they succeed or not.  (And indeed the frustration from failure can really show up the true nature of your "people").  Also worth looking at are things like can the inhabitants of your world benefit from those limitations (my Fairy Queen does, she knows nobody else can be more powerful than her) or are they seriously inhibited by them (can someone else benefit from that?).

One of Eileen's limitations is being over confident that she is always right (Jenny is keen to put that idea right but is stymied by the fact her mother often is right!) and stubborn.  That stubbornness leads Eileen directly into scrapes a more modest person, not wanting hassle, would easily avoid.