how did the first language come along?
in hobbyist days, people whose computers' only software was a monitor ROM flipped bits to write their programs. eventually people got enough memory that they could toggle in Tom Pittman's Tiny Basic (which was really popular). People knew their processor opcodes very well.
You can get the code in Dr. Dobb's Journal of Computer Calisthenics and Orthodontia. It came out every so often (I usually ended up with about 6-7 large volumes).
people would recode the languages for their own particular type of processor, whether it was a motorola 6800 or an Intel 8080 (sometimes an IMSAI if you had the bucks). games, utilities, assemblers, you name it, people were writing it. anything to make the lights blink on the front panel. and you had to toggle all 8 or 16 switches (depending on your model) to get the data in. People eventually came out with enhanced versions of their monitor ROMs that you could buy or burn yourself onto an EPROM.
People would sell punched paper tapes with the bytes on it. If you really wanted something that lasted you got mylar. And people, if they happened to have purchased a Teletype. Eventually hobbyists had a growing market for data storage and cassette tape (inexpensive) hacks and disk drives for $1000, if you had money, were available. back then in the 70's it was a lot of money.
at least that's the way it was in the hobby computer days.
long before that, programs like charles babbage's analytical difference engine (which generated interest tables I think) were hard-coded into the gears of the machinery. then things were still hard-coded with the relay and tube computers. patch panels everywhere so you could change the program. Eventually expensive tape and disk drives came along.
CP/M came along and allowed you to boot to a CP/M OS prompt like DOS, but that's an OS not a language.
so I guess you could say things kind of grew into place. In the 70s COBOL and Fortran were available on the mainframes. there were also programmable calculators (via magnetic strip).