Lighten up, it's a kids' show
No idea what people were expecting. It's shown on ITV, the most bland channel in the UK, between 7-8pm on a Sunday night, ie it's family programming, and like all "family" drama it's aimed at youngsters.
Forget about Vikings, GoT or even The Last Kingdom, this is more like Atlantis or Merlin.
I'll watch a couple of episodes but it's already turning me off, the way all the actors behave like children.