Why am I getting matched with and against Bronzes, Silvers, and even a Platinum?

Hi. I'm a really bad level 26 who loses the majority of his games. Apparently, I'm told, as I continue to lose games, I'll eventually stop being matched with these people and get put with people with similar skill to mine. This has not happened yet. Can someone explain why I get matched with these people, or perhaps come up with a solution? Here are a few of my most recent matches.

http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1729624919/217293118?tab=overview Platinum Twitch, multiple other Silvers (my most recent match at the time of this post)

http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1728628660/217293118?tab=overview Multiple ranked Silvers, Bronzes, and veteran level 30s.

http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1729619843/217293118?tab=overview Silvers, Bronzes, and level 30s.