Returning player: Where to start?

tl;dr here is: I haven't played since s1. corki, tristana and veigar are the only champions that I could tell you what their skills are off the top of my head. What should I do to get back into the game so I can start playing ranked?

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I checked around and didn't find a lot of great feedback on this topic. A lot of the getting started/learn to improve guides are written from the perspective of "Welcome to League" or "You are fumbling around in bronze/silver and want to move up".

Where would people recommend someone start that is returning from not really playing for an extended period of time?

I ask because I am kind of at a loss as to where to dive into the game now.

I quit playing after season 1 - I have jumped on occasionally for a few games here and there, mainly playing ARAM after it officially launched as game type and not just a custom type. I have maybe played 20-30 games total since season 1 ended, almost all just messing around in ARAM.

Do I just jump into unranked games or ranked games and tank until my rating drops low enough that I am with equally bad players and can re-learn everything?

When I played originally, I leveled 1-30 playing normal blind pick and by the time I hit 30 I had a working knowledge of multiple champions and was ready to benefit from more of the "improve your play style" type articles.

If I were to jump in a normal SR map today I can say that playing ADC is the only role I would have marginal confidence in not completely bending over to whoever I am laning against. I hesitate to jump into games because the idea of playing one of the other 4 roles I cannot play and then spending 45 minutes having people bitch at me for feeding and sucking sounds awful.

Is playing a few rounds vs bots worth it at all? I literally never played a bot game leveling up, I always felt it was a complete waste of time. But I also always was a marginally competent player - the handful of bot games I have played were always brain dead compared to even playing against shitty real human players.

Thanks for any feedback!