There are numerous texts in the Indian culture. Typically, you will find three types of granths (texts): krith granth, smrit granth, and vinirgrat granth. Krith granth are those which someone has written using their mayic buddhi (material intellect). There are many texts that are published every year that fall in this category. But it is difficult for us to fully trust such texts because they contain shortcomings and as a result, our faith is lacking in them. Thus, it is not wise to mold our life based on such texts.
Smrit granths are written by God-realized Saints who have been the recipients of divine knowledge, divine love, and divine love. Thus, it is Gods energy that directs their buddhi and manifests in the writings. Examples of such texts are the 18 Puranas, the Bhagavatam, Narad Puran, Garud Puran, etc. The Ramayan and Mahabharat also fall in this category. Since the source of such texts is Gods energy, we have full faith in them. And rightfully so.
The vinirgrat granths are those that have not been written by anyone such as the Vedas. The great Sage Ved Vyas only documented them; he is not the original author. Hence, the Vedas are also called apaurasheya (not written by anyone). These are considered the knowledge of God, are eternal, and are free from all material defects. Thus, they are accorded the highest respect and importance in our culture.
The Bhagavad Gita is a highly revered and cherished text all around the world. It was spoken by Shree Krishna on the battlefield of the Mahabharat. It is a concise summary of all the Vedas and Upanishads and is considered a vinirgrat granth. Watch this video as Swami Mukundananda explains the Importance of the Bhagavad Gita in detail.