Wikipedia says that the first IBM PC debuted in 1981 with 16k of RAM. https://en.wikipedia.org/wiki/IBM_Personal_Computer

I doubt anybody ever bought a 16KB tape-only IBM 5150 to hook up to their TV, but it was indeed the entry level configuration. It probably just existed to make the machine's price look good - even today all articles quote that configuration's price of US$1,565 (equivalent to $4,401 in 2019) instead of the $3K or more a practical PC would cost.

The PC could only be expanded to 64KB on the motherboard. Anything beyond that required expansion cards, each adding at most 64KB initially (which opened the door for larger third party upgrades from AST and others). With only six slots and separate cards for the floppy disk controller, video, serial and parallel ports the largest practical configuration was initially only 192KB. Not that the software could take advantage of all that (in the case of .com stuff quickly ported from CP/M, things improved with .exe).

When most people try to remember the original IBM PC they normally think of the 1983 PC XT (IBM 5160) instead which had more slots and more memory.

Around 1989 I was asked to fix a Basic program that tested car shock absorbers. It took me less time to write a new version in Turbo Pascal than it would have taken for me to completely read the source of the original program. The IDE made a huge difference but the speed was also important since it allowed me to modify and try several times per minute.

I bought one of those - added the other 48k + a 192k multifunction card - way cheaper. Even sold it on at a profit a year or so later.