5.x means it can be 5.(anything). So 5.5.0, 5.4, 5.3, 5.2, 5.anything is fine.
But if you're using version 2017-2018 then you should click on 2017-2018 version of creating a level!
You can also look on the Asset Store for some FREE tile sets!
We have this thing called the Sorting Layer and the Order in Layer.
* The higher the number, the more it is in FRONT
* The lower the number, the more it is BEHIND
In this example, 0 is the most behind and 6 is the most in front.
[Warning] If the above happens, that means they're on the same layer, the player and the tree. Did you want the tree to be behind or in front of the player?