I’m no expert on the anthropological history of mead. But if I had to hazard a guess I’d say it was probably on the sweet side due to wild yeasts doing the fermenting. They tend to die off at relatively low alcohol levels leaving higher levels of sugar in the finished product.
But that is strictly a guess. I’d also guess that pretty quickly our ancestors figured out how to manipulate the flavors to their liking.
I’d recommend that you find a quality purveyor and tell him you’d like to try a couple. You’ll spend a few bucks but you’ll likely discover something you’ll enjoy.
Sorry but that’s the best advice I can give.
You can purchase mead in Ireland. I had to cut it with orange juice before drinking. It is not sweet.