What types of subjects do artists depict in their works?
And
What are some influences?

Artists depict subjects such as people, landscapes, nature, every day objects (food, pans, and pots etc.), architecture, and historical subjects. Artists are pretty much influenced by anything and everything around them. Their influence for an artwork could come from their childhood, emotions, nature, memories, life, favorite movies, work, and other artists etc.

why are there few examples of totem poles from before 1900

hope this !