I'd say your jacket should have two essential qualities: it should be light enough to wear everyday, and it should be rain-resistant.
While the athleisure craze has not swept 'the Continent' like it has the USA, you can wear low profile, clean, neutral color sneakers in Paris.
The right purse for tourism in Paris will have four essential attributes: it's light weight, hands-free, it closes fully, and it's...très chic.
I would discourage the use of a travel backpack. You definitely won't look like a local, and, frankly, it's a huge pain.
I'd include a pair of jeans or two in your Paris suitcase. Be sure the jeans are in good shape , and a darker wash, unless you're young and cool.
DO NOT wear athletic wear, unless you are literally jogging. You can wear black leggings as pants, if you have a long shirt or coat.