You have a few options. There is more than one hut possible, so check around the island for new spots. Also, if your flowers are still dead then there are other things the builder can do. Drag a villager all over the island and see what they want to do! After you find these things, you may have to babysit them and force them to build until they get the hang of it.

All is not lost... keep going. You've still got loads of stuff to do in this game!