Islam does not assimilate, it dominates. It may take centuries, but once Islam is in the ascendant, it never fails. The host culture disappears and becomes extinct.
There is no such thing as humanity in Islam, only the duality of the believer and the unbeliever. A Muslim should never lie, cheat, deceive, or kill…..other Musims. But a Muslim may lie, cheat, deceive, or kill an unbeliever if it advances Islam.