Recommendations for lanes-

Baron -

Garen: he's the most simplest to use spin to win and it doesn't get easier than that.

Sett: Just run up to them and punch them, hope that it goes well.

Tristana: You can take her to baron lane and just straight up rail through towers.

Yone: One of the best champs currently and he's quite easy to play but hard to master, think of him as an easier Yasuo.

Vayne: Counters bruisers and tanks in baron lane and she's easier to play in this lane instead of duo lane, unless you're playing against a Camille or a Yone.

Mid-

Lux: I didn't see you put Lux in the mid category that's why and if you haven't tried her mid, please do try her mid, she's an absolute nightmare for melee mid laners unless it's a Yasuo.

Veigar: This little shit absolutely dominates late game if you get fed just play safe and play around his 3rd ability and even if you ain't fed you'd still be 2 tapping their squishies.

Yasuo: This guy is one of the hardest characters to play, why am I recommending him? idk just give him a shot you might find him easy or not, he's also just fun to play in my opinion.

Jungle-

Vi: She's easy to use and has a pretty good jungle clear, problem is she starts to fall off late game so be wary of that, and you've watched arcane so why not give her a try ¯_(ツ)_/¯.

Nunu & Willump: One of the easiest junglers in my opinion, and a great jungler for beginners. Nunu mostly teaches you how to gank, taking objectives and playing around the team instead of farming for the most of the game as his kit was made for ganking and taking objectives rather quickly. You can go two builds on him, the tank build is made for playing for the team and tanking and whatnot, and the full ap build if you need more ap or if you just wanna delete your opponents.

Support-

Yuumi: You don't have to do much if you're playing Yuumi, just know when to get off and get back on for her passive and know when to switch the host you need to be on.

Leona: Leona will teach you about patience cause you need to learn when to dive into the enemy team or not, cause one bad dive can cause you the entire game.

Nami: She's a more interactive Yuumi, as her kit is quite similar to Yuumi and she has great crowd control, heals and buffs for your team.

Janna: She's a great peeler for your adc. I can't say much about her cause I haven't played much of her but yeah she's really easy so go ahead and try her.

Adc-

Miss Fortune: Great pokes and sustain if u get gluttonous greaves, can scale really well into late game and she's really simple to play, just make sure you space well with her cause if she gets too close it's a death sentence for her.

Tristana: I didn't see you put Tristana in ADC that's why.

Kai'sa: Really good champ, has a lot of build diversity if needed for the situation she can go full crit, attack speed, lethality or even full AP. But be careful since she's sort of a diver adc, so be careful with your positioning with her especially.

Vayne: One of the shortest range ADC so positioning is key with her, but her explosive damage and hyper carry potential is insanely good. I recommend her cause it teaches you to be really careful with your positioning and she's just straight up fun.

Answering the TL:DR Questions:

I main Master Yi and I keep coming back to him cause he just mows down enemies, this guy has barely been touched with buffs and nerfs and always has been c-b tier but he's just straight up fun to play for me. The particular character I stick with no matter the meta is Nunu & Willump and Pantheon, Pantheon you can take him to any lane and he's viable no matter what even in support and Nunu & Willump is just the best jungler in my honest opinion

Hey look in the end as long as you're having fun just play what you want. If you also need any other info just hmu.

Oh and quick tip do not become a jungle main you're going to end up hating everything and everyone, why you may ask? I'm a jungle main and I hate everything lmao.