In Genshin Impact, why are all the characters I play NPCs?

Xu Guang woke up to find himself transported to the world of Genshin Impact, but there was one problem: why were all these characters NPCs?
Never mind, business is more important.
On the first day, General Thunder was very refreshed, and so was Thor.
The next day, the goddess was very refreshed.
[Day 3, Kamisato Ayaka is my safe haven!]
[Day 4, debunking the myth: Not every place where the Grass God's little feet have stepped will grow Padishalan; it didn't grow in my mouth.]
[Day 5, this one won't stick. Funinna truly lives up to her title of Water Goddess!]
【…】
[On the thirtieth day, wait a minute, it seems like Thor has become a real person?]