I started reading the bible and honestly I am already confused.

God created the earth in seven days, man woman etc... no problem I can follow that. Then just a few pages or paragraophs later people get around 700 or more years old.
Ok may be back then peopel were getting that old I still follow without problems. But then all over sudden there are sons of god in Genesis 6.

" 4There were giants on the earth in those days; and also after that, when the sons of God came in unto the daughters of men and they bore children to them, the same became mighty men who were of old, men of renown."

Are these sons of God not men?? And where did they come form already???

That is confusing can anyone explain??