Mythology is the way ancient cultures tried to explain the world around them. They crafted gods with extraordinaire powers and creatures that were a mix of men, animal and something else. Do you think Percy Jackson would have gotten very far without Greek mythology? Would Rowling thought of the Hippogriff or the Basilisk is similar creatures hadn’t already been created.
Don’t be afraid to mix and match mythologies and creatures to create characters that are truly unique, but familiar. Take the mentality of Zeus and mix with some of the physical characteristics of Shiva. What would happen if a Leprechaun fell in love with a Dryad?
The creatures and characters of mythology were so fleshed out and in-depth that these cultures actually believed they existed. They prayed and feared these creatures. You can’t get much more authentic and real than using something that people once actually thought existed.
The truth is that most writing has elements of other stories in it even if it’s subconscious. It’s these stories that thrilled us as children and stuck with us into adult hood. Don’t be afraid to take a cue from some ancient cultures and use their ideas in your book.