Getting a ninja outside from the treasures shouldn't impact the chances of you getting a ninja from a treasure. For example: people could have gotten Ay or Sasuke from events and still can get either one of them for their first kage super rare.

It makes sense doesn't it? Jiburiru just said if you get one SR from Kage treasure, you are most likely to get another one. Based on this information, you can think of the treasure as a box with 1 red ball and 1 blue ball. If you manage to get one red ball from the box, that means the next draw would be a blue ball. If you manage to get a red ball outside from that box, you have a 50% chance of getting the blue ball since the red ball is still in the box.

You need more people confirm this since if you get Ay for your first SR, you are just going to assume this is false since it's just a 50% chance at the moment.