Eh, I think you're wrong on both fronts. Lucian has a higher skill ceiling than Ashe since her kit is more straightforward. There's only so much Ashe can do, even at the highest level of play. Lucian's skill floor is way lower than Ashe. Sure Lucian has 500 range, but does he functionally have 500 range? No way. Lucian barely has to worry about positioning or trading. He has that reliable E, and there's isn't an ADC is the game that can trade with him. With Ashe you gotta focus on minion control and zoning to do well in lane, and I hardly see that even with players that I play with often that are in Gold. It seems like you're getting floor and ceiling mixed up because you're talking about optimizing build paths, that's more of a skill ceiling trait than skill floor.I mean Lucian is the champion I've played the most recently and I think she has a much lower skill floor than Lucian. Lucian's a 500 range carry that has multiple build paths to optimise his damage depending on what he's against, an ult unique to anything else in the game in terms of how it functions, a different play style to the normal auto-attacking champions.
I'm not saying Lucian's skill floor is immense, but it's definitely higher than Ashe's. Certainly from a functionality standpoint. His skill ceiling is a lot lower.
Ashe's kit is far simpler. Ashe takes more skill to play well, but playing them on a basic functional level Ashe is pretty simple and not as complex as Lucian.