warning wall of text incoming cause i might not have time to edit
the only real possibility of those champs that can be an adc is janna because she has an auto attack enhancement and a way to reposition fairly easily(her high ms with that zephyr thing) just because they are ranged does not mean they are really good or viable adc's most adc's have some way of enhancing their autoattacks and a way to reposition(the repositioning has a few exceptions like poor gapcloserless kog and varus). lets just compare some real adcs to your "adcs".
ahri and kog ahri does have a way to reposition easily between her ult and her ms boost q but has no way to enhance her auto's and scales completely with ap, kog has a w that enhances his auto range and gives him some %hp dmg he does have some repositioning issues but his e slow helps a little and his long auto range with w helps a lot to and he does have an albeit small ad scaling on ult.
next morg and lucian morg has ranged auto's and the q snare for kiting an enemy and making her hard to get to a way to make herself cc immune to reposition easily but she also has a dive in the center of the enemy team ult which is counterproductive on most adc's and her abilities scale completely with ap, lucian has a passive to augment his auto attacks his w and e help him reposition and his ult and q scale off of ad(actually not sure on the ult but i think it does) and his w and ult do have an ap scaling but he is not normally played ap.
now soraka and graves, soraka has ranged autoattacks a q that can heal her as well as silence/snare for easier kiting and she has a global ult that heals her and teammates and her passive makes it possible for her to reposition in certain situations but her kit scales completely with hp and her w is mainly used for helping allies at the cost of your own hp, graves has a dash for repositioning that also gives him an attack speed boost a passive to make him tankier and both his q and ult scale really well off of ad and his e has good utility and kiting potential.
next up lets go janna and vayne, janna i think is the closest you got to listing a more viable adc champion as she has ranged auto's a shield that also buffs her AD a way to get enemies off her and high ms with zephyr to reposition/kite more effectively but her kit does scale entirely off ap, vayne has ranged autos a passive for chasing fleeing enemies a q to reposition and enhance her autos a w to enhance her autos and e for self peel and disengage from enemy champs and possibly even cc an ult that makes her better at repositioning chasing and also gives her an auto attack steroid of course with this good kit she does have a relatively weak early and low range overall but she is extremely effective as an adc.
finally leblanc now since you didnt list another "real adc" ill simply pick one myself and im going to go with draven here actually, so leblanc has a passive to confuse enemies if she gets low has her possible 2 dashes for repositioning her chain(s) for cc and self peel and her q for amped ability dmg and ranged auto attacks but her abilities scale entirely off ap, now draven has ranged autos and his q amplifies his autos to a near absurd extreme his w gives him a speed boost and auto attack speed boost that can reset its cooldown his e is ok cc and great self peel and his ult is global AD scaling damage his q scales with his AD as well.
so most ranged adcs are determined as adcs because they have some of the following qualities: AD scaling abilities, some sort of auto attack modifier, a repositioning tool, and in certain cases (draven) absurd amounts of auto attack damage when played right. so essentially most marksman are adcs with a few exceptions(like azir who is classified as a marksman but i mean xerath is also an assassin according to riot so yeah)