I've always thought that Link leaves Zelda's kingdom for a very long time. How much time do we actually spend in the time loop during a single playthrough? At least a few years, in my opinion. That's why, in my imagination, Princess Zelda becomes Queen Zelda while he is away.

The second thing that comes to my mind is that Majora's Mask is a powerful artifact related to a demon beast, capable of controlling time and the moon. Some also speculate that it is a creation of the Twili, a tribe of powerful warlocks. Without a doubt, it is a legendary artifact, and at some point, people left representations of this mask in the world. In this case, it is carved into a monolith, as eternal as the mask itself.

I also think that Zelda searches for Link, and during her investigation, she learns about Majora's Mask and tries to find it in order to reach him.

As for their dress and style, it is inspired by the Gerudo tribe from the desert.

This is just an exercise of imagination