How do you improve when you are just that bad?

I'm playing since season 3 & honestly I'm still probably one of the worst players out there. It's because i don't care about the competition in general from losing all the time. It made me emotionally numb, that includes in winning too (rarely), so i quit for a while. Then i come back playing coop, because it's the only 'fun' i get out of this game... well that & rarely playing pre-made with old school mates. That make some spark to play in PVP again & then the cycle repeats. Done, all the tutorials, practices, custom-games, builds, basics & so on... still lose, flame, more toxicity... So then there comes up a question. Is there some custom groups that are so bad at the game, that makes custom games (pre-made 5v5s) so you could have fun once in a while or learn some new things? like how to jungle without playing coop, knowing all their moves... or normals ,or ranked, without being flamed at for feeding...?