When I started we worked in machine code. In fact when I first got my hands on a ZX80 I spent the first three weeks writing some code to emulate the Apple system which allowed you to type in hex codes and then disassemble the program you have just typed in.
Why I didn't just write an assembler I will never know, I was young and stupid.
If I did a lap around a singularity and ended up 13 with a computer today, I would probably be one of the idiots we get on this site who wants to write everything in a MMORPG from scratch.
Unlike most of them, I would have probably done it as well.
It would have been a huge waste of time of course. By the time I had finished it, the technology would have moved on and my home grown engine would be out of date.
If I was advising my young self, I would probably tell me to pick a platform. Pick an engine. Then write games. Doesn't matter how good they are, just get some games under your belt.
The amount you learn from actually completing a game is amazing. It cannot be underestimated. The things you come across that can trip you up even on a simple game will amaze you.
I once had a bug report on the Atari ST, "press these five keys with your left hand, these five keys with your right hand, and press the spacebar with your nose. Game crashes"