The build is mainly for a brand new stage for Jhin players that want to cheese on tanky top laners or just wanting to climb out. I know for starters like "Hey how come an ADC is top?" well I've played a lot Jhin top and to be honest it's really funny to see the most tanky champ run from Jhin's 4th shot. And when you try it in game. It's actually good. The top laner champs would of course be confused but use that to your advantage. Reason why is that they don't know the range of Jhin's autos and as well how strong he maybe in early phase. Jhin Top is mainly to secure the top side and grant certainty that you've won lane. I've been early ganked so many times because they think they can camp me and beat me. As long as you know how to kite and know when to auto you are fine. But if you have a problem with kiting just relax and enjoy the show of you using auto's in place and make their health go from full to half. But be mindful that standing in place is dumb so try to move around as you shoot.

For Dark harvest you can use that to gain more AD when laning. But you use this Rune's if you know that you can stomp on that top laner.

For Fleet Footwork you use this just for keeping it safe in lane its very different to Dark Harvest runes just only so you can easily escape and as well gain more crit.

Just try either one because its still a strong laning phase runes.