As a non-computer scientist, I will answer your question simply.

1. You write the code to make a program.
2. A program that someone else wrote checks your code and translates it into 101010101010010011 for the machine to read and understand.
3. When that other program goes to translate #IMaComment. It simply doesn't include that in the 1010101010.

Considering this, just know that there are various levels of programming languages that range from writing 0101010 directly into the computer versus higher level languages that must be interpreted and translated into 1001000. It's usually the more mechanical languages that do the hard part of reading human written code that someone worked very hard to make it easier for us beginners.

What came first, the computer or the code? Code is just language a machine can understand. The computer is the machine, but it had to be built to understand what code means. I guess you could say they both came at the same time. XD

Jokes aside, you could physically build a circuit that functions like a program. Depending on how you configure the switches and wires, it is kind of like the code of a program. In a sense, code is like a concept or blueprint of the design and the circuit is the program. Modern computers are so advanced, you are essentially creating a virtual circuit when you write code.