Why classic mode will not entice returning players to play the main game.

I am an old school league player. I have judgement kayle and mourn the loss of twisted treeline. I came back for the allure of league classic. I played around 10-15 games with my homies who used to play the game comming in Skype. I thought man that was a lot of fun, even with the broken AP scion games etc, maybe I should peep the main game and see what's going on.

My first thought was I do NOT want to grief a ranked game, thus I shall play SR casual (swiftplay I think it's called.)

I got assigned jungle and picked Nocturne because despite not being in classic I understood his kit. Man was I overwhelmed on start. Had maybe 10 seconds to understand modern runes, ( or maybe they don't work in SP I can't tell) I guess swiftplay is now ARAM and I get 3 skill point and a bunch of gold? Tried my best to buy items that I didn't understand and ran into the game with 4 champions I didn't know what they could do. These items were different than what I saw on the moba aggregate sites so I half built into some BS. I didn't understand the new jungle creeps and had no idea what half the champions did. I think I threw with some egregious ults.

TL;DR If riot wants to convert classic players they need a system to explain all the new items, systems, jungle creeps, champions etc, otherwise they will get farmed like me, play classic until it expires and lose out on a conversion opportunity.