Things take time. Some things don't happen as quickly as we want. We can get impatient waiting. Jesus waited until He was thirty years old to begin His public ministry. Thirty was considered the age when a man had matured enough to be a rabbi. We don't know what Jesus did while waiting. He probably became a carpenter like Joseph.
Jesus was baptized at the start of His ministry. John baptized people as a sign of their repentance. Jesus did not need to repent. He was baptized because He took our place under the Law and paid the price for our sins.
All three members of the Trinity were present. Jesus was in the water. The Holy Spirit descended as a dove and God the Father spoke. Jesus was starting to fulfill God's plan to forgive and restore sinful people to His family. Jesus sends us to bring people into His family through faith. It may take some time for people to believe. That is ok. God makes things happen in His time.