One possible moral could be that true worth is not always immediately obvious. The princess chose the tin box over the more glamorous gifts, perhaps suggesting that she values simplicity or the unexpected.
Well, the princess is clearly a main character. She is the one making the choice among different items, including the tin box. There may not be many other directly named characters. However, those who presented the gifts (even if not named) are also sort of characters in the background, as they are part of the situation that sets up the princess's decision regarding the tin box.
As of now, the Genshin manga is not finished. The story is still evolving and there's more to come for fans to enjoy. The creators are taking their time to develop a rich and engaging narrative.
There's no definite answer yet. It might continue if there's enough demand and the creative team has more story to tell. But it could also stop if they feel they've completed the story arc.
There is a Genshin Impact manga available. It brings the game's world to life on the page with beautiful art and engaging storylines. It's a great companion to the game.