girl with the camera possibly imagining that she's friends with newjeans is related to the fandom name and the other theory is that all six of them got in an accident and only the camera girl survived and that's why she's injured and she has survivor guilt so she can't stop seeing newjeans through her camera plus seeing the deer has some other meaning related to the afterlife. i'm not really sure which theory is correct but for me, i think it's just about pokemon. the title of the song is ditto which is an OG pokemon from the first series back in '99
and there's also a line in the pre-chorus that goes [Ra-ta-ta-ta, 울린 심장 (Ra-ta-ta-ta)] which is another pokemon from the OG series