Purpose: This should be the first part to consider when you create your protagonist. The purpose is how the character creates the plot of the book. What is the character trying to accomplish? What obstacles is your protagonist facing and why are they doing it? These are things to consider before fleshing out your main character. The plot will help you decide what traits to give your character.
Personality: This is arguably the most important part of creating your character because this is what will make the reader either put down the book or continue reading. When giving your character personality traits, make sure to give them traits that are relevant to the story and further the plot. The protagonist’s personality should be relatable and realistic. Everybody wants to read about positive traits and unique skills, but they also want to see flaws. We all have flaws, and sometimes the flaws in protagonists help to advance the plot of the story. How about a knight who is extremely timid? Mixing stereotypes with unique flaws and traits is the ideal way to create your protagonist.
Physical Traits: While personality is most important, the physical traits of your main character can also help draw in readers. For example, this could be race, gender, or physique. Especially nowadays, there is a lot of diversity within books regarding gender and race. This broadens the audience and allows certain readers to connect deeper with your character. Gender plays an important role in modern books because typically, girls read more than boys (not to say boys don’t read or there aren’t amazing male protagonists.) Finally, the physique of your character is important for two reasons: it helps draw in certain groups of readers, and it should reflect your plot. A character who has to carry a broadsword and armor, should have muscle. A character who spends a lot of time inside with little sleep, should appear ghastly. These are all simple ideas that could help you with creating your protagonist.