Hi Denise, welcome aboard! It's a great idea to purchase Disney's travel insurance. You'll have peace of mind that no matter what, you will be covered.
DCL's insurance does cover medical, dental, trip interruption and lost baggage, so no matter what may happen, you should have coverage. Disney Cruise Line even stands behind all claims, so that if for some reason a claim were to be denied, they would offer a future cruise to you with no expiration date, which is something I didn't even realize until recently.
I hope that helps you feel more comfortable, Denise. Of course you wouldn't plan to have any medical issues while sailing with Disney, but things do come up, so you can sit back and enjoy your cruise, knowing that Disney will take care of these issues if something does occur.
Have fun planning what is sure to be a magical cruise, Denise!