Well, that’s not true.
While it’s correct that the statutory language predominates in a question of construction, the first place that anyone would look to make an argument about how a statute should be interpreted is, in the absence of case law, to the legislative history of the bill including what the sponsors said their intent was at the time of the bill.
Now, you are right insofar as a law that says “thou shalt not kill” is probably not going to get to the point where we are arguing about ambiguity. But to say the opinions of the lawmakers are not relevant is false.