My kids are pretty creative. Most kids are, really, if they have the opportunity. Fortunately it doesn’t take much to give them the opportunity.
The first thing to do is just turn off that television. While many of my daughter’s fantasies stem from things she’s seen on TV, not all off them do. Her favorite princess, Rapunzel, comes from the fairy tale (not from the Barbie movie, which she has never seen). On the other hand, Handy Manny from the Disney Channel is her imaginary friend.
My second rule for encouraging children to be creative is to just let them be. My children play with their toys with little interference from me. This means they get played with sometimes in ways I never would have expected, but the kids are having a blast.
I also recommend having lots of art supplies and don’t worry too much about what the kids make with them. I help mine when they ask but otherwise just let them go at it. Give your children easy access to anything safe for them to use with minimal supervision, such as paper and crayons while keeping scissors and such up a little higher.
You can save some worry with craft supplies if you just spend a little extra to get the washable varieties. Having the washable crayons has meant that when my kids did the inevitable and drew on the walls they could help wash it up. Washable paints mean less worry about the eternal spills on the clothes.
Music goes great with creativity. My kids have bells, drums, a ukelele they call their guitar, toy flutes and more. Yes it does get noisy but it’s a happy noise.
All this does not have to be limited to indoor play. Little kids think it is great to strip down to the diaper and finger paint on a big piece of paper on the ground. An outdoor playhouse can become a castle, ship, store or anything else with just a touch of imagination. Kids are wonderful that way.
Most important is simply to recognize in what area your child most enjoys being creative. Anything you can do to help them explore that area is very good for them.