The Engineering Windows 7 blog has an excellent post about why the backgrounds were created, and with links to the artists. To find the artists, Microsoft worked with the agency 72 and Sunny.

There it is folks, Windows 7 is just so sharp on the ball, that even when we think it’s wrong it’s right. Odd day in tech when Microsoft was more reliable than we could have expected.

Microsoft has ended the third and final year of Windows 7 Extended Security Updates (ESU) and is urging customers to migrate to Windows 11 on a new PC or buy Windows 10 if they can't or don't want to.