How are the constitutional safeguards and test used in conjunction with the Fifth and Fourteenth Amendments in protecting individual rights?
I think that the primary level of focus in both amendments is providing for those who might have lacked a voice in consensus style politics. In the Fifth Amendment, one has the strongest affirmation for those who might be considered to be on the "lower end" of social acceptance. Articulating the rights and process for those accused of crimes presents a vociferous defense in the notion that a society that believes in rights must articulate, protect, and defend them for the lowest in that order in order to speak for them, in general. The Fourteenth Amendment extends this same voice for all those who might not have been included in the original Bill of Rights. In being able to speak for those who might have been silenced, both amendments pass a vital test in securing liberties and rights for those who might have been "passed over" in consensus style governing.
The 5th and 14th Amendments say, among other things, that the government cannot take away your liberty without the due process of law. Typically that means that it cannot take away your liberty without convicting you (in a fair trial) of a crime. The 5th applies to the national government while the 14th applies to states.
Since the early 1900s, the Court has construed this to mean that neither state governments nor the federal government can deprive you of the rights that are given to people in the rest of the Constitution and especially in the Bill of Rights.