The problem seems to be with installing Windows 7 from a USB drive and using a USB keyboard. Skylake processors apparently lack proper support for USB (unlike older processors). So that missing support has to be offered by Windows drivers, and the Windows 7 DVD doesn't come with those drivers by default.
Some motherboard manufacturers are offering help.
From
http://www.asrock.com/microsite/win7install/Intel® N3000 Series SoC and 100 Series has removed their support for the Enhanced Host Controller Interface, so you might find it difficult to install your Windows 7 operating system since the USB ports won't work.
If you were originally planning to install Windows 7 with an optical disk drive and PS/2 keyboard and mouse then you won't be affected, if not, then let us show you how its done.
That Asrock webpage probably has good information for anyone planning to install Windows 7, even for those using a different brand motherboard.
Asus also has instructions for installing Windows 7 on their motherboards.
https://www.asus.com/us/support/FAQ/1015837/Asus actually has an installer to be used along with Windows 7.
New motherboards may or may not have a PS/2 port. You can keep that in mind when choosing a motherboard. It will make installing Windows 7 easier, though you'll still have to install the USB drivers at some point.
Microsoft didn't create the problem -- Intel did. But Microsoft took advantage of the problem by not offering drivers immediately. Even now it's best to get the USB drivers from the motherboard manufacturer -- and choose a motherboard where the manufacturer supports installing Windows 7 the way Asrock and Asus do.