We need both — specific amino acid requirements for essential amino acids (that we can’t synthesize) and a more general protein requirement. Dietary proteins are ultimately just strings of amino acids, but the roles that they serve in our bodies are more complex.

This figure of amino acid metabolism gives a sense of this complexity!

Source: Metabolism of Proteins and Amino Acids https://link.springer.com/chapter/10.1007/978-981-13-1035-5_13