I give advice that people seem to really despise, and that is play with people you like to play with (because apparently saying playing with friends have people up at arms). Yes, the community is toxic, it's honestly to be expected, league, like a lot of mobas, is a competitive game that pits people against people. Naturally someone will get upset at one point or another, and humans don't exactly have the best control over their emotions, sad but true.
However, you WILL meet some people that are cool about stuff and are nice to you. If you find someone you think would enjoy playing with, just add them. A lot of people who gripe about "no one being nice" or "everyone is toxic" makes me think that they are actually the toxic ones that makes everyone else react to them. Smile, have some fun, and if you find like minded people, join them. Those are ways you can enjoy the game, so cheers, hope you get to enjoy this game.