Granted, then, that the original meaning of these verbs was stative, the fact that a number of them have more or less involuntary meaning admits of a ready explanation. From the idea of becoming, in which originally there was in all probability no idea of volition, the idea of becoming, happening independently of the will, might very readily be developed, and this may have taken place in the case of verbs with more or less involuntary meaning. After this involuntary type was once established, it is of course possible that it should have become independently productive, and that verbs expressing an involuntary action not derived from more original stative verbs should take the intransitive form. Such a process, however, does not seem to have taken place in Hebrew. The so-called intransitive verbs, therefore, to judge from the material in Hebrew, seem originally to have denoted states or conditions or a change of state, while the transitive verbs denoted actions.
Source: wiktionary