Kamal this question is very vast in terms of sense and even I never see any defined answer, Also I don’t want to take this towards what its defined in different religion and you might hear in many forums (Katha/Gita and all)
However, what I take that I can tell – for me amalgamation of Body, soul & Intellect is life. Intellect has a key role in all three. One can be acquired knowledge from external sources but Intellect can’t. Its only come with practice in life. All misshaping in life happen because of absence of developed intellect. Intellect only give you the power of decision making in life as well to know Paramatta which is again within us. If you understand the importance of intellect in life I would say you understood the purpose of life.
You can refer below my this video to know more about intellect & can refer that book which I reviewed in this video is written by A. Parthasarathy (Vedanta practicenor & founder of Vedanta word). You can also refer the Swamy Vivekananda book “complete works of Swami Vivekananda – volume1” . I am releasing this book review video next week & will share the link.