It is difficult to understand what it is you are nominating. The building bottom right, the sea, the road, the high rise buildings???
If there are multiple waypoints as you say “children’s playground equipment, exercise equipment, murals, and statues” then these can be nominated individually. NOTE: Depending on their location they may not all be used in your game of choice…
To echo SlimboyFat, I don’t see a “square” in that photo. I would not submit this as a primary image. If the thing you are nominating can be seen in this image, it might be a good supplemental photo to prove the location. You need the main image to be clear and focused on the one thing being submitted. The idea is that if someone sees the image in the game, they know exactly where to go to interact with the stop/gym or to meet up with another player.
As a general answer, if a plaza (square) is fairly large and has lots of interesting elements inside it, each of which is eligible to be a wayspot, then many of them can be submitted (but not all would appear in Pokemon Go due to wayspot density rules). Some things would be duplicates (e.g., the different playground equipment), some might be considered duplicates depending on how close or similar they are (murals, statues).
The plaza itself might be eligible if it has a sign marking an entrance, but when it has eligible objects inside it, you would struggle to also submit the plaza without an identifiable thing to represent it.
Definitely don’t submit that image as the main photo for a wayspot. It covers too wide an area and it is not at all clear what it is trying to show regarding wayspots, despite it being a nice photo.