You cannot establish a spherical shape as nowhere can curvature be observed, apart from NASA fish eye lenses.
Saying "The lights in the sky look(!) round, therefore the ground beneath my feet is also round" isn't really proof.
The observable shape is a level plane.
All bodies adhere to the same physical laws. It would be an anamoly if the Earth would not be spherical. Also, these same basic physical laws do an excellent job in describing trajectories of missiles, planes, other celestial bodies, etc, under the assumption that the earth is a sphere. Third, if the earth is actually spherical, the relative big diameter would make it look locally as a level plane to the human eye. I haven't heard a single good argument why it would not be spherical, but I am very open to alternatives and what the actual shape then should be and why...
You keep assuming this world is a similar thing as the lights you observe above in the sky. No laws make this assumption fact, but granted it is required to stay in the heliocentric trap.
Diameter is actually tiny - there's numerous observations across hundreds of miles, impossible with any reasonable curvature calculation, as required by the heliocentric model. One enthusiast (jtolan) calculated a radius in the millions after a long range observation from a plane with IR filter.
Many a globe skeptics have been made by simply deciding to dig for definitive proof of a globe. There is none.
OK, let's run with the assumption that the earth is not similar to all observable other bodies. What shape do you propose and why? Do you dispute being able to fly around the world in latidunal direction? There are many combinations of flights that cover this whole direction. So, that would rule out a disk like shape, leaving something like a cylinder. Or what other topology do you propose?
