Did God send His Guidance to Mankind?
God did not leave us without guidance. If we may call human beings a machine, we are the most complex machine on earth due to our emotions and thoughts. To properly use a complex machine, we need a demo and an instruction manual.
If you want to give demo for a washing machine, you will use a washing machine and not a vacuum cleaner. Similarly, God chose righteous human beings to give a demo to other human beings on how to live a good life. These demonstrators were the Prophets sent by God. The instruction manuals given by God are the scriptures.