What do they mean when they say “Development”?

https://larryhurtado.wordpress.com/2017/06/05/how-we-see-historical-changes/

It’s not clear, for example, that Jesus-believers of Paul’s time (ca. 30-60 CE) thought of themselves, their faith and practices as “primitive” or “embryonic” of some more mature and complete form of Jesus-devotion that might be worked out across time. I get the impression, instead, that Paul (for example) thought of the convictions and teachings that he delivered as adequately formed and fully appropriate for his situation. So, if we refer to those early years of the Jesus-movement as embryonic or the seeds of something that developed later, I think that we’re importing a value judgment that isn’t based on the evidence.