No, low light does not translate to lack of life.

However, more nutrients and more light will encourage algae growth!
I'm sorry, I can't help you with what would be a good light for your tank. There are tons of people here that can help you though. However, lowering your lights close to the water will help add more intense light to the tank.
So, literally, dirty it up! Throw some of your gunkiest sand from the QT into the DT. The more the better. There are lots of bacteria in poop along with nutrients. Scrape algae off into your DT to help seed it. Follow
@terraincognita 's advice of throwing food in there and adding hermits. Hermies and snails poop a lot! More bacteria and nutrients! (Yeah, I have a thing for poop. Poop is a wonderful thing!

)
Hopefully, the water change and everything will help fix your tank. The hermit crabs will be a testing ground. My fingers are crossed this will do it. Good luck!
P.S. The nitrifying bacteria will grow on anything in the tank. Like your sand bed and plants. And that's what is handling your ammonia. You don't 'need' rock per se, but good rock will house tons of bacteria. A very good thing!