In the book of Acts, why were all of the people in the examples of conversion  baptized immediately?

It is about the sense of urgency for baptism when the convert learns that baptism is "Unto the remission of sins", Acts 2:38 (past sins) No one should leave that matter to chance, due to the gravity of that ordinance.

In one all was lost in one all was saved. The one brought death to all, the one brought life to all.

Water immersion baptism actually has an in-depth meaning. Consider the words given to John the Baptist when he was hesitant to baptize the Lord Jesus:

"Permit it to be so now: for thus it is fitting for us to fulfill all righteousness." (Matt. 3:15).

What did the Lord Jesus mean when he said “fulfill all righteousness”?

In Exodus 40:12-13 we read: Then you shall bring Aaron and his sons to the door of the tabernacle of meeting, and wash them with water. You shall put the holy garments on Aaron, and anoint him, and sanctify him, that he may minister to Me as priest.

The Lord Jesus Christ Himself, in order to minister as the faithful high Priest in the priest’s office, needed to be washed by the baptism of water (Heb. 2:17; 4:15; 5:5). If the Lord needed to do so, how much more then do believers need to do so? In 1 Peter 2:9, it is written, But you are a chosen generation, a royal priesthood, an holy nation, His own special people (Ex. 19:6; Rev. 1:6). The believer, without a doubt, needs to be water immersion baptized, so that like the priest standing in the priest’s office he can offer spiritual sacrifices to God (Heb. 13:15; 1 Pet. 2:5).

"Some" (Protestant denominations) teach just about anything you can think of. However, Jesus Christ founded one Church, said it was to remain one, and promised that one Church that it would teach the fullness of God's truth until the end of time. That one Church has baptized new members since apostolic times , and will continue to do so forever.

they were ready willing and able to be baptized so they were baptized. Although it is not necessary to be baptized, even Jesus was so they were also

Much of Acts is fabricated. Luke borrowed Mark and Matthew's Gospels to write Luke and Acts. Neither Luke nor Paul was ever a disciple or an Apostle of Jesus. Luke became a disciple of Paul 17 years after Jesus' crucifixion in 30A.D.. Luke used Acts to introduce Paulism/Romanism which became Catholicism. When the last 5th of Mark was destroyed by a fire in Syria in 69A.D., a bogus 12 verse ending was added by Luke, Mark 16:9-20. Theophilus had Luke rewrite 'Mark' and 'Matthew' to please the Roman Government and never returned the original manuscripts to their rightful owners.

The Catholic Church has always taught the necessity of baptism, for salvation. The Bible clearly says that the time for salvation is now. It's obvious that all those assembled there, under the powerful inspiration of the Holy Spirit, received and believed that critically important message. Something must have been lost in translation by the time the 15th century (and later) Protestants came along.

The penitent woman (Luke 7:37-50), the paralytic man (Matthew 9:2), the publican (Luke 18:13-14), and the thief on the cross (Luke 23:39-43) all experienced forgiveness of sins apart from baptism. And there is no record of the apostles' being baptized.

IF U WISH TO KNOW, ASK A TRINITY PASTOR SUCH AS METHODIST OR PRESBYTERIAN.

When I opened this question, I was sure it was going to be another one from Norine.