It's fiction. Kensuke's Kingdom takes you into a fictional world crafted by the author's creativity. There's no real-life basis for the story or its elements.
The Last Song is a work of fiction. Usually, it involves elements of creativity and imagination to craft a story that doesn't directly correspond to real-life events or people.
It's a mix. The show is based on historical events which are facts. For example, the Viking invasions and the existence of various kingdoms in England during that era are real. However, some of the specific characters' storylines and relationships are fictional. They are created to make the story more engaging and dramatic.
The Last Kingdom is fiction. It's a historical fiction series. It takes place in a historical setting, but many of the characters and specific plotlines are made up for the story.
The themes of 'The Last Kingdom' fiction include survival. In the violent and chaotic world depicted, characters have to fight to survive against various enemies. Also, there is the theme of honor. Many of the main characters uphold a certain code of honor, whether it's in battle or in their interactions with others. Friendship is also a theme, as some characters form deep bonds in the face of adversity.