The antonyms for the word "most high-level" can be "low-level", "basic", "entry-level", "elementary", "simple", or "rudimentary". These words refer to things that are less complex, less important, or less advanced. For instance, a low-level employee is someone who holds a junior position in an organization, whereas a high-level employee holds a senior position. Similarly, basic or elementary knowledge is something that a person learns at the beginning of their educational journey, whereas high-level or advanced knowledge is something that a person learns later on. In general, antonyms of "most high-level" refer to things that are less significant or require fewer skills to understand or perform.