Well, leadership is also a key theme. The slime character has to lead his newfound community and make decisions for their well - being. There's also the theme of exploration, as they explore new lands and encounter different races and cultures.
Rimuru is definitely one of the most interesting. His transformation from a simple slime to a complex and powerful leader is fascinating. Then there's Shuna. Her loyalty to Rimuru and her skills in cooking and management make her stand out.
The exploration of different magic systems in the Tensura Slime Web Novel is quite interesting. Rimuru discovers and masters different types of magic as he progresses. This, along with his attempts to introduce modern concepts like economy and governance to his growing nation, are important aspects of the overall plot.
The slime protagonist is definitely one of the most interesting. Its unique ability to absorb and gain powers makes it stand out. Then there's Rimuru, who has a very complex personality and is constantly evolving.
The plot involves Rimuru's journey from being a rather weak (initially) slime to becoming a very powerful being. He meets many interesting characters. For example, there are the goblins he befriends early on. Rimuru helps them improve their living conditions. As the story progresses, he also has to deal with the threat of other more powerful monsters and even some human kingdoms that view his growing power with suspicion. In general, it's a story full of adventure, growth, and the forging of relationships in a magical and dangerous world.