Why am I playing with Plats and Diamonds when I JUST hit level 30?

So I'll be the first to admit, Im not a very good player, I rarely have the time to play these days. Now I just hit level 30.....I have some basic AP quints and that's it. So why is it in every game I am going up against Diamonds and Plats? Wtf is this match making Riot? Not only are these players 10 times better than me, but they also have all runes setup.

Its like graduating from the highschool basketball and then going up against the Lakers the next day. I feel insanely bad for my team-mates because I just get shit stomped in every lane. I basically have to go support just so I can do a little bit of assisting and just don't completely give an entire lane away.

I also can't play ranked to get myself in the elo I deserve because you don't make nearly enough IP to get enough champs and runes to qualify. I also don't want to waste what IP I DO have on small IP champs I don't like. I'd like to save for Azir, Zed, Swain and some other champs I will enjoy. Bad design Riot.....just bad all around.