The Gospels and Biographies of Abraham Lincoln
This isn’t a perfect anecdote, but I’ll share it none the less.
I've read a number of Biographies on Abraham Lincoln, the earliest from the late 1800s down to about 2004. It's not always the case, but if I took four common examples, lined them up on my bookshelf in chronological order you'd notice something very quickly. Each is successively larger; this is because the biographies became successively more in-depth. Each one contained more events (or different ones,) and more explanations then the earlier ones.
Should I therefore conclude that newer biographies were made up? Clearly Lincoln is hailed as more and more important a President who's legacy grows larger in each one --- therefore it must be made up!
Well of course not, as time went by more things were learned, more connections made, and more things needed to be explained as the context and time spanned further apart. I view the Gospels in much the same light.