If we are to understand a particular baptism form of life we need to learn the language games that the author takes for granted. Words such as water, repentance, sins, forgiveness, Spirit each have a different meaning depending on the language-game in which they are used. But we also need to grasp why Mark chose to include that particular form of life in his Gospel. With a good writer the art is to include what is needed, and only what is needed, to make the point. In the case of the Gospels the point is to clarify what the good news is about, and elicit a response to that good news by the readers or hearers.
Every religious text has some kind of good news to communicate.
But the intended response is very different in each kind of religion. An original Buddhist wants you to lose all desire. A Hindu Monist hopes you will learn to merge with the Absolute. A Confucian text require you to submit to tradition. A Taoist text frees you from tradition.