No, the Torah does not state specifically that one should not wear jeans, neither does the gemorra. The Torah also does not state specifically for example, what kind of linen one should put on their guest’s bed, or how big of a smile one needs when being mevaker choleh. The point being that the Torah was given to people with sechel, the Torah is our guide and we need to make choices accordingly.
The gedolim are our guides who have a much deeper sense of spiritual reality then we do (hence the name gedolim) and we need their guidance in such times. Essentially they give a sense of spiritual security in the guidance they share.
What a person wears is a message to themselves and others of who they want to be seen as. A person wearing a sailors uniform will be assumed to be a sailor. Whether we like it or not what we wear will be seen by others, and depending on how you feel about that clothing, that is the choice that the person will make. It doesn’t define your essence, it just defines on how you want to be seen.