The Jesus Itinerary

[Lion IRC]

…During the first few centuries CE, the early Christians were rivals of the followers of John the Baptist, known today as the Mandaens.

I think you have made a typo here.
Surely you mean… there were rivals. Not,…'they were' rivals.
It is obviously false that all early Christians were automatically rivals of John the Baptist and/or his followers.
John the Baptist was in jail and executed. His followers were, therefore, obviously perplexed and fragmented.
But…..
Jesus told His followers, whoever is not against us is for us.
Does that sound like a them and us paradigm?

…The Mandeans believe that John the Baptist was the messiah. All four Gospel accounts include passages where JtB puts himself down, declaring that he is merely a forerunner for Jesus.

John the Baptist is elevated by all four Gospels and by Jesus.
Jesus compares John to Elijah.
Yes, of course John is humble.
Sorry if humbleness doesn’t fit your idea of a servant of The Lord.
Have you read Psalms lately?