i suggest people read some theology on the Gospels. The intent of the Gospels was to speak about who Jesus was, to the original audience.
They are not intended as a biography. At that point, everyone knew about the Historical Jesus. Everyone knew what had happened. The big questions were why who and how.
Look at the speed with which the Good news of Jesus spread through the Meditteranean in the first few centuries. Jesus was fresh in everyones memory. The radical , the rabble rouser, the man who stood up for the marginalised and the poor. The Jew who ate with sinners , prostitutes and tax collectors. The Jew who challenged the Sadduccees, the temple leaders and teachers. And the pharisees
Each Gospel was written to a different audience. And Jesus is a different person in each. For example , Mark has the Historical Jesus, the human Jesus as the suffering servant. And this is because at the time Mark was writing , Christians and Jews were being persecuted and were suffering. So Mark gave them courage with the example of Jesus in His suffering.
yes Luke wrote his Gospel and Acts. Luke is regarded as a great literary writer. His work is extraordinary. He was talking of Jesus to a gentile audience. Talking of the Historical Jesus, in His humanity, as a saviour to all.
Yes Oral tradition and time and certainly distance separates each author. Although we know Matthew and Luke drew on Marks Gospel and on other sources, i.e. Quelle. Quelle was an oral source as well as thought to be a written source, destroyed when the temple and Jerusalem was destroyed. Matthew and Luke are considered to have written after the destruction , or at the time of the destruction of the Temple.
I have not said there is less historical value.
I have said, the authors did not intend the Gospels to be biographies, or history books.
The intent, theologically speaking and validated by many theologians,
was to explain who Jesus was, the significance of the Risen Jesus.
John wrote in the AD90s, he has a more spiritual Gospel. He firmly placed Jesus as the Passover sacrifice. the Passover lamb. It had much more to do with that then Pharisees and Sadducees. when John was writing, all Jewish Christians had been exiled from their homeland and were living in the diaspora and well beyond.
When Matthew, Luke and John were writing, post and current to the Temple destruction, the Sadducees had all been decimated too. They were the leaders and custodians of the Temple. They were destroyed. But the Pharisees then took over, after the Temple.
So when we read the Gospels, in the first instance, we must place our interpretation of them from within and behind the Gospel reading. Within means what was happening at the time the Gospel was being written, who was it being written to , then behind is who was the Author, how is he describing Jesus and Why.