But wait oh ,who were those other people?

So after breakfast this morning, I was just doing the dishes oh and as i stood by the sink, I just thought about Adam and Eve when they were in the garden of Eden enjoying, till when they sinned and were kicked out by God.
They had two male children abi, our ancestors Cain and Abel, then Cain killed Abel, God cursed Cain ,he became a vagabond and a mark was placed upon him so that anyone who saw him as he roamed the earth wouldn't kill him, I want to believe I'm not mistaken. This brings us to the question Who were those other people who weren't supposed to kill Cain? if in the beginning god created Adam as the first man and eve his wife and they were the only ones on earth.