Why Namaha is added to as the prefix to every Mantra?

Every Mantra the prefix of Namah is generally added.
Na means ‘negation’ and Ma means false ego or Ahamkara. Therefore Namah means surrendering our Ego at the alter of God

Second meaning for the Sanskrit word ‘namaha’ means _ Nama _ means ‘ not mine” ; that which does not belong to the person who is doing Puja , ( flower ) he is offering to GOD, since every thing belongs to HIM only.