最初 (zuì chū) is a noun meaning 'the beginning, the initial stage' and is often used adverbially as 'at first, originally'. It neutrally refers to the starting point in time or the original state. Compare: 原来 can also mean 'originally' but often implies a later realization ('as it turns out'); 初 (chū) is a more literary prefix (e.g. 初次, 初级) rather than a standalone noun.