I don't know any Jennas, but I'm not in the born-in-or-near-the-80s-and-90s category. So it's not that surprising.
I've never cared for
Jenna, to be honest. To me it's like
Tessa and
Christa, I much prefer the originals (
Jennifer,
Theresa /
Tess, and
Christine /
Christina).