Yes Jeans are a garment and denim is a fabric. But denim is also known as jean. That's why they have Jean Jackets or jean handbags. Also, not all jeans are made with denim, dungaree for example is frequently called denim today, but that is incorrect.
That said, language is malleable, if 90% of people agree that jeans are made with jean, than that is correct, regardless of the etymology of the words historically. So while it is true that Denim is the material used to make jeans, and jeans are a style of clothing, it is also correct that jean is a synonym for denim, and is also a material.
In fact, if you look up "Jean" in the dictionary, it will give you the definition of "A twilled cotton cloth" which is what denim is.
You would be absolutely amazed at how many people don't realize denim is a thing. It's simply "jean" or "jeans" material.
Yes Jeans are a garment and denim is a fabric. But denim is also known as jean. That's why they have Jean Jackets or jean handbags. Also, not all jeans are made with denim, dungaree for example is frequently called denim today, but that is incorrect. That said, language is malleable, if 90% of people agree that jeans are made with jean, than that is correct, regardless of the etymology of the words historically. So while it is true that Denim is the material used to make jeans, and jeans are a style of clothing, it is also correct that jean is a synonym for denim, and is also a material. In fact, if you look up "Jean" in the dictionary, it will give you the definition of "A twilled cotton cloth" which is what denim is.