I enjoyed reading this topic. In my opinion, the issue is very simple. it is all about general relativity principle. For example, the moon looks like a Sphere or circle (((with respect to someone watching the moon from earth))). But if that person travel to the moon, then the moon will be seen flat in shape but ((((with respect to someone watching and walking on the moon))).

Same thing should be applied to the Earth. In your above example, the earth was painted as if you were looking at it from outside the atmosphere. However, those who built the tall buildings, they built those constructions based on/from the walking-inside angle of view. Did you get it ? As for why this could happen ? the reason is due to something in mathematics called limit of functions i.e lim(x)=infinity towards a constant number.

Moreover, it is due to our size with respect to the earth size. for example, we cannot move on the surface of a football. However, if you put an Ant on the ball, the ant will move straight because it will see a flat surface because of its small size with respect to the ball size which is too small. So the ant will not able to recognize the actual spherical shape of the ball due its small size. This is exactly what is happening to a man moving on the earth. His size with respect to the earth's size will not give him the ability to recognize the actual spherical shape of the earth. It is all about observer's angle of view.