The key fact here is that there are different levels, or “registers”, of English. The level of common speech includes the 3,000 or so most common words, the ones learners should focus on studying and using first. Many of these words are based on the Germanic origins of English, like “house”, “daughter”, and the verb “to get”. The “higher” level or more formal register is full of words that largely came into English from aristocrats, scholars, and scientists. These words are from a form of French, or Latin, or Greek, and they are more specialized for different areas like medicine, law, and the sciences, and more upper class experiences like having dinner parties instead of raising farm animals.
Many Latinate words are very commonly used too, but in general they sound more formal, refined, and educated to speakers. It’s the difference in meaning between “to get” and “to acquire”. Using more aristocratic (which itself comes from Greek and means “of rule by the best people”) words isn’t the best choice in some situations.
Native speakers talk about clear writing as something that uses simpler, more common (lower register) words as much as possible. We also say that more common speech, with more Germanic-origin words, sounds more sincere. “I appreciate you” is more formal, more detached, than “I love you”.
Native speakers’ vocabularies also differ based on the type of work they do, the amount of education they have, and what class or race they are. Each of these contexts has special vocabulary, and speakers don’t usually know many words outside their own areas.
What all this means is that learners should get that common vocabulary first. Then think about what you want and need to do with English. Are you working in IT? You should focus on that vocabulary and not literary terms. Are you going to spend time in an English speaking country? Learn practical language for common tasks and some slang. Etc.