This is the first one I have no idea what it is.
Evert may be right. It seems to be for sure a shrub if not a tree.
Looks like one of our Ash (Fraxinus) saplings that pop up all over our garden.
Well I have looked all of your suggestions up and I'm sorry to say after looking at this little fellow so closely, it's none of these.
It does seem to be a tree though.