If after 500 years Nahida just looks like she is 10 at most... how old was when she was Rukkhadevata?... How old is Klee?... How old is Alice?
The reason she looks young now is because after using all of her power to save sumeru, her body morphed from an adult looking goddess to a smol goddess
Nah, the accurate comparison would be Marchosias and Guoba, the same individual that used too much power and made him shrink.
No, the archon quest had nahida meet Rukhadevata meet and Rukhadevata explains it in almost the exact same way the person above did. Nahida is a seperate being. Rukhadevata used up her power and became smol waaaaaay before nahida was born.