They opted for a fairly simple machine with easily available hardware, based on the fairly new Intel 8088 chip.
After a failed deal with Digital Research to use CP/M-86 as the operating system, they chose Microsoft's operating system 86-DOS (a clone of CP/M-86 from Seattle Computer Products). For IBM it was shipped as PC-DOS while Microsoft retained the right to offer it as MS-DOS for other computer vendors.
Besides PC-DOS, the machine was also equipped with IBM Basic.
The first IBM PC series came with 16 to 64K memory and optional floppy drives. It also has a connection for a cassette player to load or save software.
MS-DOS / PC-DOS 1.00 supports up to 320KB floppy disks and did not support directories. Until the 2nd version of PC-DOS was an improved version of the IBM PC on the market with support up to 256 kB memory and 360 kB floppy disks.
Considering the use of readily available hardware and the BIOS that could easily be recreated or passed over to directly address hardware, combined with IBM's already known reputation, the IBM PC is much copied and the de facto standard for all current PCs.
The market for the IBM PC was not the average consumer, but focused on working from home or more business use. This computer did not intend to play games on it.