When writing the script, he deliberately chose modern dialogue and colloquialisms, such as when Tom Holland’s Telemachus refers to Matt Damon’s character, Odysseus, as “Dad” rather than “Father” in one scene.
Article source: https://www.huffingtonpost.co.uk/entry/christopher-nolan-defends-odyssey-language_uk_6a4e4b71e4b094d71e71475e