I think Liam Hemsworth is a decent enough actor. He's not particularly special, but he's capable. It's quite possible they're giving him the role, not because of his acting chops or his physical features, but because he's an established name, has the schedule free and will commit to as many seasons as Netflix will film, is reliable, and quite possibly has the right contacts and influencers pulling the strings. He also possibly accepted a reduced wage in place of Cavill in order to seal the deal.