Don't really want to assume too much seeing as the account I post on is extremely misleading if you look it up, but your op.gg says plat 4 mate...
I mean I'm D1, and I post on this. So its totally possible you also don't post from your primary account, but I've been pretty unique for years and years for always posting on this account so I kind of doubt that's the case.
In any case, I think the advice you're giving in this thread is very misleading. Low level players should play a champion they feel comfortable with whose play style feels natural and like an extension of their personality. It really doesn't matter what champ you pick or what the difficulty of the champion is, only that its played extensively (even exclusively, that's fine, one tricking has been for 4 straight seasons the most successful method of climbing the ladder) so that the game play pattern becomes so familiar as to become reflex, allowing low level players to improve at the one thing 99% of all league players in rank lack: understanding of the game at a strategic level. Honestly, mechanical ability really isn't very important to climb the ladder, understanding the game, having good in game sense and awareness, strong organization and communication skill, knowing what points in the game you and your team have the advantage and why, where to be when and what to do when you get there and all these other strategic elements are vastly more important and you really just can't learn them if you are constantly learning a champion. It doesn't matter if you play a difficult to play champ like Azir or Zed or Eve or if you play a relatively simple champion like Amumu or Annie. What matters is whether you know what to DO with the champion at all points in the game and whether or not you can coordinate a gameplan with your teammates.
In case you wanna look stuff up: http://na.op.gg/summoner/userName=Likeamaws
Hell even my one trick smurf is higher ranked than you in a role I only decided to start playing this season: http://na.op.gg/summoner/userName=ev3carriesu
Sure easier champs to play are easier to play. But the game is about mastering the game if you are looking to climb and the best way to do that is to pick something and stick with it for a long period of time until you start to understand what is actually important to win games. I feel like this is much better advice to give to players. I know the students I took on this season progressed rapidly from low silver to diamond using this advice despite the fact both played difficult champions, Zeretov is a Lulu main and Mr. Trianglez plays Ahri.