Like other NFT projects, some items in Slingshot 2099 are more rare than others. The total number of each identical item is displayed on the Slingshot NFT marketplace when buying or selling items. For example below, the green coat on the left is rarer than the black shirt on the right (153 green coats vs. 298 black shirts). Rarities range from as few as 9 to as many as 865 identical items. A list for all available items and their rarities is here.
If you were airdropped a Genesis Bag and have not yet claimed it, you will see an animated notification next to your account menu on the top right of the screen. Clicking the animation allows you to claim your pack via your connected wallet. Your wallet must be set to the Polygon network in order to claim your Genesis Bag.