I can play Jungle, but will always ask my teammates to swap with me because it's probably my worst role. Just because the guy said he didn't know how to jungle doesn't mean that's true. He may know but not know well enough to play it to the level needed.
The only thing I think is really needed is an actual tutorial. The tutorial is horrible at explaining how to play, bot games don't teach anything except just hard pushing one lane, and normal games are so skewed that you can have Bronze players vs Diamonds. The only effective place to learn against players of similar skill to yourself is in ranked, which leads to the current situation we are in now where fresh 30 accounts are being placed in high Silver games despite not knowing how to play.
The easy solution I'd offer is lowering where unranked players start. Instead of placing fresh 30's in high Silver, place them around Silver 5 or even Bronze 1. Obviously that would suck for people trying to climb out of Bronze, but I don't think starting a bit lower would hurt a fresh 30 if they are actually a Gold+ player. Additionally, instead of a Bronze 3 player instantly being placed Silver 2 and losing constantly for a while, they would only fall a few ranks before leveling out, meaning less accounts would be affected by the inaccuracy of his starting place.
Another solution someone mentioned was having trials you had to complete. Something like "get X cs in X time", "complete this jungle path", "set up a slow push", etc. These are good starting objectives, but I don't know if it would truly prepare someone for ranked.
Another I'd recommend is a "win a 3v5 Intermediate bot game" (or even a 1v5 bot game), because while bots are dumb, they help you learn objectives to a degree. Being in a disadvantage like that teaches you about trading objectives, split pushing, and defending against siege to a degree since you can't be everywhere at once.
Now, all that said, you've only played like 30 games, which is way too small a sample size to draw any conclusions about anything. One day last season, I had 5 games (3 in a row) with an AFK or a trolling teammate that lost us the game (and I mean teammate openly saying, "I'm gonna troll cause this Yasuo took my farm" or "no help top, I'm AFK"), 3 of which were during my Gold promo. And yeah, that day really sucked because I knew I was losing but not because I played badly but because someone decided they didn't want to try.
That aside, that was also my 5th or so time getting to my Gold promo, and some of the previous attempts I made mistakes for why I failed them. You too probably make some mistakes yourself that you don't even realize. Additionally, consider playing champions that synergize together so that even if your team is bad, perhaps you both can carry due to you having the communication advantage to combo together properly.
