Thought about starting...

I have though about starting LoL cuz some of my favorite streamers play it.
Is the community really toxic, and how hard is the game?

Hi,

I would like to help you but the problem is that I do not know LOL, I hope that another person can help you.

Absolutely! The game obviously has toxic players, as any other competitive game does. But that is not a thing that you should worry about, it has a really fun learning curve, when I look back at how I started playing this game, it was super fun. Regarding the difficulty of the game, depends on what do you call a hard game. Personally for me, the game wasn't that hard to pick up, but that may be because, when I start playing a new game I tend to watch a lot of content about it and ultimately improve, gain a lot of knowledge.

I can't speak to what the community is like now, but I can say that I stopped played because of anxiety related to the game and some of its community.
All games have trolls, and studies have shown that teams that start to lose turn abusive towards their own members. I distinctly remember several games where I was being outplayed by the opposing team or made a few errors and then I got shit on by my teammates and that made me super stressed and more likely to screw up again later.
There are vs AI modes that allow you to learn some basics without having to deal with as much troll nonsense and still enjoy the game (which I still contend is well made), but playing too many of those risks locking you in sub-optimal playstyles because you didn't have to adapt to higher level play techniques.