While it is possible for that to have been added in as a comic relief to a serious situation by the redactor scribes, I feel that doesn’t take away from the seriousness and possible historical nature of the event as told in Jonah. It is possible that the redactors did add in those elements to make a point in the irony of Jonah being a disobedient prophet and God getting His Will done through the unfaithfulness of Jonah, having pagan sailors praise God and other elements.
I feel that part of Jonah (Jonah 2) is meant to Jonah in a near death experience situation (I feel that Jonah was in a sense in-between life and death while in the belly of the sea beast and thus he was in a sense in Sheol, the place of the dead.) And God had the creature vomit Jonah out and thus restored him back to life. The whale and the sea are motifs for the grave and death so it would make sense for both Jonah and the later redactor scribes who later wrote down the oral account to notice and make this point a priority.