The Earth is indeed round, but the curvature is not always apparent to the naked eye due to the Earth's large size and the limitations of human perception.
The curvature of the Earth becomes more noticeable when viewed from a significant altitude or distance. For example, when you observe the horizon from a high vantage point, such as an airplane or a mountaintop, you can often see the curvature of the Earth. Similarly, photographs taken from space clearly show the spherical shape of the Earth.
However, when we are on the surface of the Earth, the curvature is not as readily apparent because of the relatively small section of the Earth's surface that is visible at any given time. The Earth is quite large, with a circumference of approximately 40,075 kilometers (24,901 miles), so the curvature is subtle over short distances.
Another reason why the curvature may not be easily perceived is that our vision is limited in its ability to detect small changes in shape or geometry over large distances. Our eyes have a limited field of view, and the curvature of the Earth is a gradual change over a vast expanse. Additionally, our brains often perceive the horizon as a straight line due to visual cues and the way our eyes interpret the world around us.
However, there are several ways to indirectly observe the curvature of the Earth. For instance, the phenomenon of ships appearing to sink below the horizon as they sail away is a result of the Earth's curvature. Similarly, the existence of time zone differences and the ability to see the sunrise or sunset at different times in different locations are consistent with a spherical Earth.
Scientific measurements, satellite imagery, and space travel have provided abundant evidence supporting the spherical shape of the Earth. The notion of a spherical Earth is not a theory but a well-established scientific fact supported by extensive evidence from various disciplines.