I said I don't claim much knowledge of Egyptian or American archaeology
You say this.
But then follow with this
just seems that like so many other disciplines there is an unwillingness to consider potential discoveries that don't fit current theory.
It might seem like that when you don't know much of it, but like with the Pre-Clovis example: the bulk of it is just simply there's no good evidence for a claim versus the amount of evidence that goes into "mainstream" idea.
This also tends to paint the mainstream as a monolith of single opinions when there's a large diversity of opinions. They just fit themselves in with the accumulated facts.
For example, just sticking to the archaeological evidence. The pyramids definitely date to the Old Kingdom. There's some debate about the exact century, and what the state of it was when Khufu started building his pyramid. But carbon dating of coal from the mortar and thermoluminesce dating put the pyramids in the Old Kingdom.
The quarry the stones used to make the pyramids is where the sphinx sits. Without a pyramid's worth of stone being pulled out, you don't have a quarry, and you don't have a sphinx.
Multiple lines of evidence point to the pyramids and the sphinx dating to the Old Kingdom, so why take claims about them being 12000 years old and built by Atlantis s seriously?
can, for instance remember the Viking settlement at L'Anse aux Meadows being dismissed by some at first.
Sure. And then genuine artifacts were excavated by practicing archaeoligsts. This doesn't always happen of course, Schmidt didn't get any dismissal when he announced the age for Göbekli
I do think that we don't fully understand the various contacts between ancient cultures via trade routes
By the bronze age trade reached from Egypt to the balkans. There's various bits of evidence of trade among the old world. But none between the old and new world.
Most of the well known ancient religions derived from the Paelo Indo European pantheon, or were influenced by them. Egypt and Sumer mostly excluded. Chinese traders were buried in ancient Greece.
Nan Madol is going to require a re think of the history
Not really, Hancock popularizing it again doesn't change the number of pieces of research that's already been done on the site, again people making fantastic claims in liue of good evidence doesn't get traction anywhere except people trying to sell "The truth the won't accept."