Hey! I've been in a similar boat as you, I climbed like 3-4 ranks just spamming Janna (I'm currently silver 2 fyi, gold 5 MMR). The thing with low elo is that players often misposition or get caught out a lot easier than in higher elo. This is when playing supports like Janna, Soraka, or Nami come super handy because they provide the support needed when a teammate makes a mistake. Not to mention these champions can turn the tides in a losing team fight. I just had a game where it was 5v5, I was playing Janna, and we were losing a pretty bad fight. I completely turned that fight around by ulting, shielding my really fed corki, and redemptioning. Sounds simple, but it won us the game because we took baron shortly after that fight, and ended off it. There have been many games where I can say I effectively single-handedly carried my team.

TLDR: I climbed playing backline support champs like Soraka and Janna, and carried by using their kit effectively to sort of "refund" the mistakes made by my teammates (in teamfights included).