is jennie the national idol?

the only other "it girl" who comes to mind is yujin from Ive (depending on one's definition of IT girl)

Yes

and Lisa is too

of 3rd gen, obviously

I am glad she is free from the dungeon, hope to see her doing more appearances. All members are fun in variety shows

I think the last girl that I can definitely say is the national idol was Yoona.

There's too much competition these days plus Jennie hasn't been that active. Maybe it'll change this year when she has more activities.

National Idol is an appropriate title for Jennie.

Kpop's It Girl is Wonyoungie. But Jennie probably has broader demographic appeal, stretching to include older men and women, while Wonyoung is focused on the young and very young (everyone knows how beloved she is by preteens and their parents lol).