A forum can't just be about only 1 single topic. It needs to expand to form a community with it's members.
I can understand a lot of in-jokes and memes are confusing for newbies, but you just have to live with it. It won't make you a better member if you do learn old in jokes anyway. For a reference, A lot of regular members (Including myself) all joined 2007-2011 and they've made a home here.
Like STM said, just have fun.
And as for past members, I do miss a few. Mostly T-Nex though.
Oh and Max the Mug. I wonder where he went?