Acts 2:37-39
Young's Literal Translation
37 And having heard, they were pricked to the heart; they say also to Peter, and to the rest of the apostles, `What shall we do, men, brethren?'
38 and Peter said unto them, `Reform, and be baptized each of you on the name of Jesus Christ, to remission of sins, and ye shall receive the gift of the Holy Spirit,
Sounds like remission of sins is the purpose.
1st Peter 3:21
The water of baptism is like that. It saves you. It does not save you because it washes dirt from your bodies. But it saves you because you bring yourselves to God with a clean heart. It saves you because Jesus Christ has been raised from death.
I trust Peter over your human conjecture.