Amex's No-Fee Business Points Card
If you want one simple points card for "everything else," this is it. 2x on all purchases up to $50,000 each year (then 1x) with a $0 annual fee is easy math. Just don't use it overseas—there's a 2.7% foreign transaction fee.
Normal people can get business cards. If you sell on eBay, drive Uber, freelance, or resell a few sneakers, that's a business. Apply as a sole proprietor using your Social Security number; no corporation required. It's straightforward and very common.