When even a ghost that can't talk feels REAL, you know it's a good novel. Just the way the author describes its actions and facial expressions... really surprised me for a web novel especially.
Also, the MC being reincarnated actually works well in this story as his educated and modern thinking helps him.
So the MC starts out as a relatively average and normal person, but suddenly becomes:
1) master tactician
2) master fighter
3) master alchemist
4) master engineer
5) master creature creator?
Even though we are in a futuristic setting, it still feels like modern day or earlier.
Even though we are spread out across the Milky Way and other galaxies, it feels smaller than the Earth.