Not sure how low your "low elo" is, but my advice is to play a champion or champions that you enjoy/like/resonate with, etc. If you enjoy a champion enough, their mechanics wont seem like a chore to learn, regardless if they are complex or simple.
It is said that you can climb to diamond 4 with about ANY champion in the game if you know them well enough and can focus on your macro. I know that I personally climbed from Bronze 5 (when it still existed XD) All the way to silver 3 as Skarner top lane. Im currently Gold 4/3 and still love playing this champion. (EVEN THOUGH RIOT SEEMS SET ON NOT FIXING HIM RIGHT NOW!)(Sad face for me)
But yeah, focus on learning how to win the game, but play a champion that you enjoy. Follow guides and watch gameplay to get a jump start on how they work in general, and then adapt the champion to your playstyle or visa versa. Have fun and dont flame! :)
Ironically, just found this thread:
https://boards.na.leagueoflegends.com/en/c/league-videos/p6fUBszG-illaoi-pentakill-illaoi-montage-season-8