According to Islam, why was I born?

Why was I born, according to Islam? In fact, I also have a second component to this question. If Allah/God is omniscient, then why did he create beings that he knew were certain to enter hell (which he also created)? Even assuming he gave us 'free will', he **knew** when he created us who would end up 'choosing' hell. So why would he create them? Is this not injustice? I kindly ask for answers in light of the Quran and Sunnah, as to distinguish this question from merely delving into philosophy.