Thanks for putting all those available signature campaign in one thread sir. Unang apply ko ng signature campaign sa whyfuture hinde nman natanggap 
It's actually Mitchell (Mod/Staff) who put that together and Fatanut who regularly updates it. I just shared the link for the new users who didn't know about it.
Anyway, yes I think they only have slots remaining for Sr/Hero/Legendary Members.
Just keep on checking those campaign threads for available slots. Meantime, a few weeks lng naman and you'll rank-up na, mas marami na options then.
Here, so you have an idea:
The activity number is determined in this way:
time = number of two-week periods in which you've posted since your registration
activity = min(time * 14, posts)
time = number of two-week periods in which you've posted since your registration
activity = min(time * 14, posts)
Rank Description:
Activity
Newbie: (none)
Jr. Member: 30
Member: 60
Full Member: 120
Sr. Member: 240
Hero Member: 480
Legendary: 775 - 1030
So, Keep at it. ^^