What is purpose? A drive for meaning and understanding, or accomplishment? What is life without purpose, can it be that we have no purpose inherently built into us? Must we have purpose, and if not, then what is life? Can we not ever actively be seeking this purpose? Without are we miserable?
deep purpose is the cause part of cause and effect. life is because your parents had sex and the sex cells joined successfully. the effect part is for you to answer yourself. this drive or motivation is what you accept and refuse in the world. there only very few things we all have inherently built into us, but mind is a vague tool or aspect that changes upon environment and conditions. and that is why when consciousness happens, there are overwhelming possibilities, in which in this case i think this is happening to you, an existentialist crisis. read some books by existentialist authors, or just research it, you'll find it fascinating. and many people feel miserable without purpose, like raising children or supporting a family member or w/e, but it's not always the case, and thats due to one's perspective on purpose. like what qualifies as a purpose can be completely different between people. someone might be completely content with constantly buying jackets from this certain store because the world wouldn't be the same without that person buying all those jackets. one person may only qualify the purpose of life is to reproduce. but the point is is that you will affect the world no matter what, and in one's perspective, that should at least be good enough as a purpose. if you want to make it more complex and specific, then fine.
There is no purpose. I think it's human nature to want to feel important or superior. Mankind, for some reason, has developed this mentality that he matters. There is, nor has there ever been, at least he assumes, a species so great as us, and therefore we matter. I however, think man takes himself to seriously. We don't matter. There is no purpose. We live, and if we're lucky, we propagate more purposeless beings. But there really is no purpose that we are here for. And a lot of people, born into this "man is superior" way of thinking, would find this depressing. Most people have an inherent need to feel important and needed. I however, don't. It's freeing, actually. We don't have any purpose, so we might as well enjoy ourselves. We don't have to strive for anything or become anything, unless, of course, we want to. Basically, we're here to have fun. We serve no more purpose then insects or rodents, we just last longer. Humans, in all honesty, have probably done more damage to the earth then any other species. I say we just take it all for what it's worth and celebrate our freedom to do anything or nothing at all.
Read Ayn Rand's non-fiction, followed by Nathaniel Branden, Leonard Piekoff, David Kelly, and you will be a lot closer to understanding what's what, and why it is that way. Peikoff's book, OBJECTIVISM, THE PHILOSOPHY OF AYN RAND is a great intro, but it's 700 pages of post-grad level work, no comic relief at ALL. Dont read it in bed, or you'll fall asleep in 10 pages. It's heavy stuff, but it's great. Ayn said:"Life is its own purpose, The good is to live it". That's enough of an answer for mature, logical people.