Whatever contend including photos that have put on my Ancestry public trees was put there to share.
I would suggest if you don't want anything copied ,then don't put it there or make it private.
My trees with Ancestry are private but the information is still accessed by public. I called them and they had no real reason why this happened. So now I just photocopy and keep the info at home.
There are some I will save to the tree but very little