Uh, no one said the Constitution didn't apply to the states. You seem to have a habit of incorporating statements in your argument that no one actually made.
And, yes, even laws against extreme crimes like murder, rape, arson, etc have to be passed at the state level. Why? Because the Constitution does not explicitly address those things. There are Federal laws against those crimes as well, but those only apply in very specific circumstances (like if they occur on Federal property).