"The observation that the inclination of the sun varies with latitude" obviously is "evidence that the earth is curved and not flat"
from our perspective.
Yet you probably deny the fact that birth figures after demographic transition primarily depend on death figures (under not too anomalous conditions) or that an increase in male mortality leads to an increase in the male/female sex ratio. So, 2000 years ago, you simply could have put into question the fact that the sun (in Egypt) stands generally higher in the south than in the north.
You also could have argued that it is well known that light can deviate from a straight line, e.g. when entering or leaving water, or in the case of a mirage. The hypothesis that the sun is not always where we see it, might have been much easier to digest than the logical consequence that things fall upwards on an opposite side of the ground.
You even could have argued that the sun is not at an infinite distance, and therefore different angles are observed from a flat earth. So instead of deriving an Earth's circumference of around 40'000 km, you could have used the same data to calculate the distance of the sun from a flat earth:
On the summer solstice at noon, the sun was directly overhead around 800 km south of Alexandria. In Alexandria at the same time, the sun deviated from this zenith by an angle of around 7 degree. Because we have a right-angled triangle, we can easily calculate the sun's height to around 6500 km.
Let us assume, person of the past already knowing that the Earth is a sphere would have claimed that two locations exist, where a half a year is "day" and the other half is "night".
What could this person have done, if a skeptic, not being able to imagine that the Earth is a sphere and therefore dismissing the demonstration of the Earth's sphericity, would have requested a proof?
Nothing! The insight of the existence of the two poles depends on the insight that the Earth is a sphere.
Only within a theoretical framework such as
pandualist evolution it becomes possible to demonstrate (or rather: to make plausible) special cases of reincarnation chains.
Cheers,
Wolfgang
Galileo dismissed as a "useless fiction" the idea, held by his contemporary Johannes Kepler, that the moon caused the tides. Galileo also refused to accept Kepler's elliptical orbits of the planets, considering the circle the "perfect" shape for planetary orbits. WP