"If ancient Indians were so advanced in scientific studies, why no Indian discovered the round shape of Earth?".
In reality, ancient Indians knew about Earth's round shape. In most cases, temple sculptures show the Varaha Avatar lifting the Bhudevi (Earth) in humanoid form- that is depicted as spiritual aspect. That is the popular architectural style due to religious influence where we worship Earth as a Goddess.
However, in some rare sculptures, the Earth is also depicted as a spherical globe with or without the humanoid form of Bhudevi.
However, in some rare sculptures, the Earth is also depicted as a spherical globe with or without the humanoid form of Bhudevi.