I'd suggest that you give it time until eps 4 or 5 at the very least, since the show is at its best when it's a pure mystery. It faked me out with the most generic initial premise of "Big bad has revived after X time, and it's up to X people selected by an ancient goddess to stop him!" and the awful as hell CGI fiends, but it got really interesting when it switched gears into focusing on the mystery of who the seventh (fake) brave was.
Too badthe finale episode introduced another brave again, meaning they're likely to be back to doubting each other once again next season (if it ever gets adapted).
About your spoiler:
Even though the premise of "there's a 7th" is the same in the 2nd book, it plays out completely different, mainly because the reader actually learns at the beginning who it is and there are many scenes from the 7ths pov. There's also a second main mystery.