The easiest group of your champs there are junglers, but jng has the extra difficulty of the pathing, I said that it depends more on champs than role but I should've made a exception on jng because jng itself is harder on macro than rest of the roles by default.
For supports you like playmaking ones, definetely not the easiest supps, Morgana is quite simple but not the other two.
For adcs you also like some tricky ones that have high skill ceiling by the cost of being harder to learn. If you want easy mechanics dont play Xayah and Lucian.
Midlane 2 control mages and 1 "go in" mage, that could be the lane you are looking for but I'll say that Viktor mid is lackluster right now. Vlad is the hardest one to learn there.
As I said Kayn Nunu Graves are the easiest ones on mechanics but is jng so keep that on mind.
And for toplane Darius and Trynda are pretty easy to play specially on low ranks but the thing about toplane is that is such counter centred lane and that's something I dislike, but that's my personal view. You could play them, and Kled is harder but neither is a Nidalee or Kalista lvl of hard.
With that champs and if you are looking for the easiest mechanics I recomend you jng or top, with mid being third and the last two supp-adc in either order.