Here's the opening of my middle grade novel. I'd appreciate your advice, or just an opinion about all that's wrong with it.
People always thought the Earth had a molten core with magma bubbling over a red-hot metal ball. I don’t know. Maybe it was that hot centuries ago, but then it got hard and stone-cold like someone had left it outside in the freezing night. We discovered it when in the search of the remained energy sources, we got right in the center, and came third to the site. I was not there. Well, I could not be. At the age of four, you were not allowed to go digging in those times. But my uncle likes bragging about being there among the firsts. To tell the truth, it was quite an amusing story the first hundred and something times. Now, whenever he starts retelling it, we just get him his favorite pine resin to chew. The best way to shut him up for an hour or so. An hour is a great deal. After all, there are only seventeen of them left a day.
You see, since the earth got pierced from like five places and some genius thought of using the tunnels as a kind of underground, things did not get better at all with an opportunity to get to the other side of the planet in… well, no one really knows how long it would take. The only time still frozen on the flip-down clock over the ruins of the Corecentral Station is 29 minutes. That’s exactly how long the train lasted in the tunnel.