Fiora basically easier than garen to lane with and is based of game knowledge rather than champ knowledge (stop looking at 1v5 montages)
Lee Sin basically has the highest playrate in jg with a fairly normal winrate so its I wouldnt say its that difficult for a 1 time pick (they literally want to push him as the go-to jg champ, same story with Thresh
Lb is probably the only semi hard on the list but shes excelent for getting filled on as she is really safe at mid and can easily do the minimum reqiurement for an assasin with point and click.
Vayne literally designed as a low ranked pick and has always had a higher winrate at the lower ranks and from experience, ik vayne can win a game without even knowing how to kite.
U have a really good and relatable point i just think ur def of easy and hard isnt that great but ill upvote nvertheless.