If you have read Datta Darshanam book, you would have found your answers. This book has been published in all languages. Even regular reading of the monthly magazine Bhaktimala clears all such doubts.
The answer is the creator Brahma noticed the infinite souls in the creation. He filled them with life and mobility so that they can attempt to travel towards Brahma-loka or Go-loka, the final abode.
The cow eats grass and gives milk, which in turn is used to prepare yoghurt, butter and ghee. We cannot obtain these items directly from grass. A cow is needed to convert the grass into milk. There is a definite process for everything.
Like dust particles, all the living entities were hanging in space. We were there since the beginning of time. Brahma, who is filled with infinite compassion, decided to create a mechanism by which we are able to return to our permanent homes. He thus created the karma system.
Even before that, He created the concept of Guru. This Guru was none other than Dattatreya. In other words, the leader was created first. It is also like supplying multivitamins along with the antibiotic. Antibiotics without vitamins kill the good germs along with destroying the bad germs. Multivitamins ensure the continuance of the good germs and thus avoid side reactions.
Once Brahma put this system into place, evolution began. But the human beings decided to dump the Guru principle and lead an independent, reckless lives. If you lead your life as advised by your Spiritual Guru, then Brahma will use short cuts to take you to your destination.
Sewage water needs proper distillation method. For instance, the Sunrays clean it and then this water evaporates, transforms into cloud and falls down as pure rain water. Likewise we too need to be cleaned and purified. This does not mean you should give up your family lives and lead an ascetic life. It is not possible. It means you should at least begin to think why you are born.
Brahma has given us this birth to uplift ourselves. Make use of this great opportunity.
(Q&A Malaysia, 30 Mar 2001)