I am not going to cite these midrashim inside, and thus will not discuss every single input into formulated these midrashim. For example, there are 69 people listed, yet the pasuk says 70 went into Egypt. Bereishit 46:27:
The midrash that suggests that it was Yocheved, who was born as they entered the gates, is based in part on Bemidbar 26:59:
born but not conceived to Levi in Egypt. Thus, she is not numbered among them.
This has repercussions, such as: we calculate the 400 years of servitude in Egypt from Yitzchak, such that there are 210 years in Egypt (rather than an explicit pasuk stating 430, which would make it even more difficult). Moshe was born 80 years before the Exodus, and so Yocheved must be 130 when she gives birth to him.
This is a miracle, to conceive and give birth at such an age. True, there are precedents, such as Sarah who gave birth at 90, but then the pasuk states that this would be an extreme age, such that it was miraculous. Sarah laughed, after all. And would the verse omit such an astounding miracle? It must be figurative.
Yet. The pesukim do state that Amram married his aunt, daughter of Levi (though I have a radical way of resolving this, stated in another post). If she was born later, Levi must have fathered her later in life, and it still only stretches so far. Furthermore, there is a real, peshat-based impetus to this midrash - 69 people are listed, yet 70 is the number given. True, there is the irregularity of counting a daughter, but then, Serach bat Asher is listed among the 69. And saying that Yaakov is among the yotzei yerech Yaakov is plausible yet has its own difficulties. Further, the miraculous age of 130 for giving birth is not the start of the midrash, but only a side effect. And midrashim often have no difficulty assuming miraculous events, such as turning invisible to remain unseen by Pharaoh's soldiers. No. I would not take this miracle of birth in old age as proof positive that this midrash was not intended literally. It resolves practical narrative difficulties, and miracles are par for the course.
Of course, there is a thematic element worked into all of this. There are three suggestions for the identity of #70. It could be Yaakov. It could be Miriam. Or it could be, as a midrash has it, Hashem.
How so? A few pesukim earlier, in Bereishit 46:4, we had Hashem promise Yaakov to go in with him to exile, and to return:
|ד אָנֹכִי, אֵרֵד עִמְּךָ מִצְרַיְמָה, וְאָנֹכִי, אַעַלְךָ גַם-עָלֹה; וְיוֹסֵף, יָשִׁית יָדוֹ עַל-עֵינֶיךָ.||4 I will go down with thee into Egypt; and I will also surely bring thee up again; and Joseph shall put his hand upon thine eyes.'|
Still, Hashem is not a descendant of Yaakov, and, as with many midrashim involving Hashem, I am inclined to take it homiletically. (Perhaps yerech yaakov could be taken as a promise, as Eliezer promised Avraham, in which case it can work out.)
There is a similar theme, I think, to Yocheved being born as they entered Egypt. Yocheved was, after all, the mother of the redeemer. It is quite poetic for the potential for the redeemer to enter the world just as they enter the beginning of their exile, by entering the gates of Egypt. This is in keeping with Hashem's promise. It was not a promise really only of accompaniment , but of the fact that they would eventually get out of this servitude, and were not being abandoned forever to servitude in Egypt. This is aside from the derivations from various pesukim like Bemidbar and difficulties in counting, which I touched on earlier. The theme is also present, guiding interpretation.
Would this be homiletic, then? I would still say that there is enough to ascribe literalness to this midrash, or at least not dismiss it. Many a literal midrash plays into and develops a general theme. Still, realization of this theme enriches our understanding of this midrash.
The second midrash is that Aharon struck the Nile and the dirt because Moshe had hakarat haTov, to the Nile for hiding him and to the sand for hiding the body of the Egyptian. To this, there are no miracles attached. It merely ascribes a motivation to facts recorded in the pesukim. There may be a tendency to state that this was intended literally.
Yet, I would take this particular midrash figuratively or rather homiletically. Besides the fact that the Nile and the sand had no choice in the matter, and that it seems silly to act in gratitude to inanimate objects, we can consider other elements of the midrash. Is there a real problem that this is solving? Sure, there is an impetus to explain why certain actions were performed by Moshe and certain ones by Aharon. But this is not a "problem" in the same way that numbers not adding up is a problem. One can simply say to this, "Nu, nu. Aharon functioned as proxy, as his navi, several times, and there was some reason for this."
But further and actually foremost, the main goal of this midrash appears to be homily. The source text is pretext to teach the important lesson of having gratitude, such that we see that Moshe even had gratitude to inanimate objects, and to things which did not deliberately intend to do him good. We thus learn something about life rather than learning something about the narrative.
Thus, my inclination would be to label this homily.
Of course, there are aspects to both of these midrashim that might lead one to make another interpretation. The values here are fuzzy. But I thought that my judgments in assigning literalness or lack thereof to these midrashim might elucidate what sort of factors I assess.