"Thou shalt not kill", self-evident vs. it is so because it says so in the Bible?

The Bible says "Thou shalt not kill". Now to me this is a self-evident concept that I have understood since an early age. Once I understood the concept of death the concept of its immoral to commit murder just seemed a logical followup.

So why is it some need to read in the Bible that murder is wrong for it to be believed that it is wrong?

How about "Thou shalt not commit adultery"... or... "Thou shalt not steal"... or... "Thou shalt not bear false whiteness against thy neighbor"... or... "Thou shalt not covet"? Are these things wrong because it says so in the Bible? In the absence of the Bible would they still be wrong? IMO they are just self-evident truths that any who have the ability to think in a rational and logical way will easily come to understand on their own.

My morality was learned mainly through experience and observation. For example; As a small child the first time a kid stole a cookie off my plate was an object lesson in the immorality of stealing. And as a small child when I saw a kid take a toy from another kid it left me filled with a sense that I had just witnessed a wrong being committed.

IMO as morality comes from the mind of mankind, it is as old as mankind and predates all the modern religions.

The reason that I say morality is "self-evident" is because morality is an intangible idea that we cannot prove by any scientific method. Morality resides in the heady world of philosophy, theology, ideology, sociology... etc.