Here, I'm only guessing, but IF Jacob's hand grabbed Esau's heel and it keeps saying Esau was the firstborn, I am not an obstetrician, but somehow I think Esau came out first...no big deal, the Bible keeps talking about it--that Esau was firstborn. I can't see what the problem is yet. (Insofar as your idea is concerned, do you mean that Jacob really emerged first from Rebekah's womb? not sure what you think here.)
In Exodus 13:2, we read the Lord telling Moses to sanctify all the firstborn, i.e., all those who "open the womb" פטר כל–רחם. He tells Moses that all "womb openers" uniquely belongs to him; which is to say all "womb openers" (the mother's firstborn,
ben lakohen ב׳ לכהן) will be his priests.
Thus, prior to the golden calf fiasco at Horeb, all Jewish mother's firstborn ("womb openers" פטר רחם) were slated to be priests in the house of God (they all belong to God). But because of the fall at Horeb, and since only the Levites were willing to slay their brethren at Moses' command, God established a specialized-priesthood (the Levitical priests) to replace the former universal priesthood of Jewish mother's firstborn. After the failure at Horeb, the priesthood would come only through the Levites. Which is to say that though formerly the priesthood was transferred only through a Jewish mother, after the fall at Horeb, the father's fathering-organ gets into the act since tribal identity is patrilineal, i.e., an inheritance through the father.
The priesthood, which wasn't patrilineal before the horrible fall at Horeb, now became related to tribal identity, and thus patrilineage (it could be inherited through the father rather than the mother). This priesthood (the Levites), which wasn't a worldly inheritance (related to the father) prior to Horeb (it depended only on being the firstborn of a Jewish mother), now became a worldly inheritance related to who your father is, and what tribe he's from. Which is to say that whereas prior to the horror at Horeb a mother's firstborn/womb-opener inherited his Jewish identity and the priesthood exclusively through the mother, after the fall at Horeb the father's fathering-organ got into the act such that now the father's testes got to testify concerning what was originally based soley on the mother.
Flashback from horrible Horeb to Esau and Jacob. For in their day inheritance of the priesthood and Jewish identity came exclusivelyh through the "womb opener" (the mother's firstborn) since the Levitical priethood, based on what tribe your father comes from, didn't yet exist. At that time it's of the utmost importance to know, if you have twins, which one "opens the womb" first since he's the favored firstborn who inherits Jewish identity and the priesthood.
Voila! This is the context for the story of Perez and Zarah. Zarah's "hand" comes out first, but then retreats back into the womb (having had a scarlet string attached), while Perez is thereafter born before Zarah. If not for the red thread, Perez would inherit the priesthood as the mother's firstborn and Zarah would be falsely reckoned the younger brother.
In the story of the birth of Esau and Jacob, Esau's "heel" (euphemism and all) "opens the womb" with Jacob's hand wrapped around it so that if there were a midwife on the scene, in the text, ala the story of the birth of Perez and Zarah, a scarlet string would be attached to Jacob's hand so that although Esau, like Perez, is born first, Jacob, his hand coming out ahead of Esau's "heel" by a finger's breadth, is thus the true firstborn (since his hand opens the womb), and Esau, like Perez, is the usurper who comes out first when he's actually the younger.
In Hebrew, the word for Esau's "heel" is עקב. Add the letter
yod as a prefix and you get the name Jacob יעקב. As a prefix, the yod tells us Jacob's name is the third-person future-tense of the word for "heel" עקב. As noted previously, the Hebrew word "heel" עקב, is used in other places in the Tanakh to cover up the fact that its speaking of the phallus. And since the literal meaning of the word means "supplanter," or "usurper," it means Esau's "heel," like every "heel" (male-organ) used to "father" offspring, is a "usurper," or "supplanter" (see signature at the bottom of this page). This means the name "Jacob" (עקב "heel" with a yod prefix), signifies that Jacob is the name/person whose birth signifies the "usurping of the usurper, the supplanter of the supplanter" (i.e, the third-person future tense of the word). His birth, i.e., his hand opening the womb rather than the usurping organ opening the womb, that is, Jacob's "hand" (rather than the organ that usurps every birth from Cain to Christ), supplants, usurps the "heel" (male-organ) that's been arrogantly and errantly opening the womb from Cain to Christ.
Someone will say, but the story of Perez and Zarah comes after the story of Esau and Jacob? And in Judaism the firstborn narrative supplants latter stories, the earlier story being the firstborn story so far as Judaism is concerned.
Which is the primary point of all this since spiritually speaking you need the story of Perez and Zarah to properly interpret the story of Jacob's hand being wrapped around Esau's usurper such that using the later story, which is thus the true firstborn story, we can know that Jacob's hand beats Esau's usurping organ to the punch by a hand's breadth so far as opening the womb is concerned, so that we know the spiritual truth that Jacob isn't a usurper, Esau is. Jacob is the one who usurps the usurper ---as his name implies.
Flash forward to the story of Jesus' hand opening the womb when there's neither a twin in that womb nor a fathering-organ involved in opening it prior to Jesus's conception and birth. His hand opens a completely closed, hermetically sealed, womb (a virgin's closed hymen), to signify that he's the womb-opener par excellent. His birth completely supplants the supplanter, the male-organ, which is the unholy "heel" in the Gospels, the organ Jesus' birth completely usurps in every way (see signature at bottom of page).
The story of Jesus' virgin birth is the scarlet string attached ---retroactively ----to Jacob's hand, telling us that even though the malfeasant Masoretic text would like you to believe Jacob stole the right of the firstborn, and Judaism seconds that emotion, since she thinks Jesus too is a supplanter (rather than the supplater of the usurpers par excellent), in truth neither Jacob nor Jesus are usurpers, but rather, the sanctified supplanters of the profane usurpers. Jesus and Jacob supplant the organ and all organs that would have you believe Jacob and Jesus are ********, chisselers, cheeters, rather than those who are being cheated in the fallacious Masoretic rendition of these narratives.
John