In fact, your statement is confusing as to what you mean by diversity and how that was changed by Constantine.
What I meant by “diversity had always been there until Constantine changed it”, for example:
Acts 23:8
(The Sadducees say that there is no resurrection, and that there are neither angels nor spirits, but the Pharisees believe all these things.)
Despite the Pharisees and the Sadducees taught different teachings, they all worshipped in the same temple. And the people listened to their teachings which sourced from the same scriptures they read to the people in the temple by the firstborn of each family who happened to have their turn to do so.
1 Corinthians 1:12
12 What I mean is this: One of you says, “I follow Paul”; another, “I follow Apollos”; another, “I follow Cephas[
b]”; still another, “I follow Christ.”
13 Is Christ divided? Was Paul crucified for you? Were you baptized in the name of Paul?
14 I thank God that I did not baptize any of you except Crispus and Gaius,
15 so no one can say that you were baptized in my name.
17 For Christ did not send me to baptize, but to preach the gospel—not with wisdom and eloquence, lest the cross of Christ be emptied of its power.
Despite there were different opinions among the leaders, which sometimes caused people to have heated debate, I’m sure, but there was no war neither definitive schisms, because nobody seek to define what **formal **schisms was.
Instead, they taught "to have no division, despite there were disagreements"
In other words, they allowed debates & diverse opinions as long as it were sourced in scriptures. Thus, scripture quotes were thrown freely in synagouges and in the open spaces anywhere any inspired teacher taught, as long as they could attract an audience.
Jesus was able to teach at the synagouges at the time, because of this climate of freedom of religion enforced politically by the romans.
Paradoxically, the same empire, under converted Constantine, he decided to use religion for politics, to unite the Kingdom. And under him,
despite his intent was to unite the kingdom, in doing so, he had successfully define what formal schism was/ is.
Probably it was good to define errors. However, the use of weapons & political power, I’m sure had presented great challenge for those who wanted to speak the truth.