Trust me, I know how you feel.
Like I said, when I go to normals its for practice or to earn a chest on a champ.
I end up with the AD bot lane Soraka with Master Yi support while Im trying to earn an S on Amumu... The enemy team has a tryhard comp and they all have a stun. Normals is a shitshow. Those tryhard players in normals may aslo be using it to "warm up" after not playing for a week. The rest of the time they may be feeding their ass off playing Jinx top lane to troll people in normals.
The only thing Riot could do is link their normals and ranked MMR... then, you would suffer the "hard to practice" issue in normals. You would be playing a champ your new at against people of similar skill level who still may not be using champs they dont know how to play.
The problem is people perform very very VERY differently on champs they have less experience on.... look, let me put it this way... a lot of people play this game. Not enough people play it at the same time for Riots match making to pair up people of similar skill level, who will also play champs of similar experience... what champ you play and how experienced you are with them is decided after the match is made.
As for levels below 30, simply a problem of there not being enough sub level 30 players to match them with unless they want to wait in 8 minute que times. It sucks, but getting into an established game and being new is tuff. I agree with people who say Riot doesnt do enough to get newbs into the game, and it is often awful for them. That said, there really isnt anything Riot can do because even if they leveled out the normals somehow, there will always be people willing to troll 5 games straight for whatever amusement that gives them, then tryhard stomp people playing a champ for the second time.
Last note, I started this game in the late part of season 4, and this season has been the strangest thing as I pick off meta supports people whine and cry more than Iv ever seen and will even dodge games in normals if they dont like my pick enough... there is some strange new breed of tryhards in normals.
Im not being a dick when I say this, but your only hope may be a second account where you play champs you want to practice on in ranked. Its part of why so many people have smurfs. Theyre Gold level support, mid, bot, but want to test their jg skills a bit more without tanking their MMR. So they make a smurf to play jg champs in ranked.
Look, I want people to enjoy the game and have fun. I feel like you should get to grow in an environment that supports that, but people exist, and a significant portion of those people are fucked up assholes. Im telling you, Riot cant do what you want.