I think you're overstating the importance of land bridges. The English Channel is narrow and hunter-gatherers have crossed much greater bodies of water, like in Oceania. Actually, water is essentially a teleportation device: you arrive by slow foot travel to some coast and end up on the opposite coast pretty quickly.

But everything is different when you go to prehistory, it seems hard for us laymen to imagine correctly. A given band of hunter-gatherers would not have travelled far in one generation. And I don't really see why the Stonehenge couldn't have been erected by a culture that had not even met another culture for a hundred generations. Look at the statues of Easter Island (https://en.wikipedia.org/wiki/Easter_island).

The specific way of stacking massive rocks as seen in Stonehenge (upright with horizontal on top) is spread far and wide across Europe, found in almost every country. Using that exact same "design".

Hardly a coincidence, I'd say.

Agreed, but the ones in Britain all date from much, much later than the inundation of the land bridge.

Agriculture predates stone-henge and the major oceania migrations by quite a bit so "hunter-gatherer" is probably a misnomer in those cases.

As far as we know, land bridges were crucial to major migrations during the time periods this article discuses.

I think you are generally confusing quite different pre-historical periods.

I do think it is quite reasonable to suspect that the ability to cross the english channel predates stonehenge.

The Oceania migrations started 60,000 years ago! Agriculture was experimented with early on in some places, but agricultural civilization with all that comes with it is a different thing. That's taken to have started popping up about 10,000 years ago, but very slowly. It came to Europe with the Indo-Europeans, so about 4,000 years ago, long after Doggerland (submerged 8,500 years ago). Agreed?

It is actually quite likely that the fertile lands of Doggerland were an important centre of European civilization at the time.