The environment that you have created in Tiled is great, but at the same time, it is a bit empty. Have a look at this portion of the environment now: 

Thus, we need to bring decorative props into it! Thankfully, our package comes with great props, such as trees.

If you didn't, slice them with the Sprite Editor, to have all of them on different sprites. Then, drag them into the world and fill it as per your taste. Just remember to set the right Sorting Layers for it. In my case, I would go for a Sorting Layer of 0 or -1 to be aligned with the terrain or behind it so the character will pass over it. In case you want to create an obstacle or a collectable, you can place it to a higher Sorting Layer, such as 2 or 3. However, you need to remember to add a collider for it (and set isTrigger to true in the case of collectable, along with an appropriate script).

Here is one possible result in arranging props in the level:

Finally, don't forget to share your creation, and to use your imagination and add props designed and drawn by you. Also, don't forget to add a nice background as well. You can find one in the graphics package you have downloaded.