TTWSYF, yes theoretically it should be like that. But remember, Hebrew existed for nearly 2000 years before it died off. During that period it had a developmental phase (time of the patriarchs, Moses), stabilization phase (time of the judges), bloom phase (David and Solomon), split (north vs. south), deterioration phase, (Babylonian exile), etc.
Bible narratives have been taken from all these phases. Changes in the language would have occurred as it was influenced by the languages of surrounding nations, e.g., Ugaritic (in the time of David and Solomon), and Aramaic (Laban was a Syrian, also Aramaic would transplant Hebrew after the Babylonian exile).
Some of the above changes are evident in the development of aspect/tense of the language. Early Hebrew concentrated on aspect (state of the verb), whereas later Hebrew leaned towards tense (past, present, future).
Another problem with Biblical Hebrew is its limited literature corpus, which consists of the Bible, inscriptions, the Cairo Genizah, and a few DSS MSS. That is not nearly enough to trace its development with any degree of accuracy or certainty, thus the educated guess work by scholars. They have done exceptionally well in working it out, but there are many gaps.