I believe there should be a folder that you can drop and drag Heroes into that you are not currently using or leveling. The deeper the bench the more confusing it starts getting.
I’ve got so many Heroes I will never get around to leveling so I have to scroll and scroll in order to find the feeders to feed the ones I am feeding. It would be nice to be able to put those Heroes that I’m not ready to work on yet into a folder to clean my inventory up. Just click on it and pull them in or out