Allah is the creature who created all things you see around you living or none living. He did not create for any reason but he created us to worship him and he granted to feed us to give us the best reward afterlife. Some may say that there no reason behind this life and nature is what created us...
Prophet Mohamed is the final messenger that Allah sent after Prophet Jesus. Allah gave him last revelation, Quran, which is the word of Allah. The messenger is a mercy and gift that Allah gave to the mankind to guide the right path in order to save them from the hell of fire.