Regarding this verse, it is written in the Medrash -
אִשָּׁה כִּי תַזְרִיעַ (ויקרא יב, ב), הֲדָא הוּא דִכְתִיב (תהלים קלט, ה): אָחוֹר וָקֶדֶם צַרְתָּנִי, אָמַר רַבִּי יוֹחָנָן אִם זָכָה אָדָם נוֹחֵל שְׁנֵי עוֹלָמוֹת, הַזֶּה וְהַבָּא... אָמַר רֵישׁ לָקִישׁ אָחוֹר זֶה יוֹם הָאַחֲרוֹן, וָקֶדֶם זֶה יוֹם הָרִאשׁוֹן - אִם זָכָה אָדָם אוֹמְרִים לוֹ אַתָּה קָדַמְתָּ לְכָל מַעֲשֵׂה בְרֵאשִׁית, וְאִם לָאו אוֹמְרִים לוֹ יַתּוּשׁ קַדְמָךְ
[Leviticus 12:2] - "A woman who conceives"
That's what is written -
[Psalms 139:5] "You have created me behind and before." Said Rabbi Yochanan: If man merits, he inherits two worlds, this one and the coming one.. ..Said Reish Lakish: "Behind" - that's the last day. "Before" - that's the first day.. ..If man merits, we say to him: "You were created before all of creation." If not, we say to him, "The mosquito preceded you."
From this we can infer, if humans were created last after everything was already in creation, then how can we tell him that if you are worthy, you have proceeded all of creation?
And we will answer, with the help of Heaven to preface with what I saw in explaining the following verse -
Regarding this verse [of Jacob stealing Esavs blessing], the Medrash comments and says -
(בראשית כז, לה): בָּא אָחִיךָ בְּמִרְמָה, רַבִּי יוֹחָנָן אָמַר בָּא בְּחָכְמַת תּוֹרָתוֹ
Your brother came with guile - 'Rabbi Yochanan says - 'He [Jacob] came with the wisdom of the Torah'
And here we need to clarify, as Esav is coming to complain that Jacob stole his birthright, so what type of answer did the Medrash give here when it comments that Jacob came with the wisdom of the Torah, which was specifically because of this he was permitted to take the Blessing in an unjust manner. However, it is understood that the sages here are asking how is it possible that Jacob was able to take the blessings of this world, because didn't we learn the below?
ויתרוצצו. מִתְרוֹצְצִים זֶה עִם זֶה וּמְרִיבִים בְּנַחֲלַת שְׁנֵי עוֹלָמוֹת.
ויתרצצו They struggled with one another and quarrelled as to how they should divide the two worlds as their inheritance, ..so they made a split amongst themselves, Esav would take this world, and Jacob would take the world to come.
If the above is true, how was Jacob allowed to take the blessings of this world, when it was agreed already to belong to Esav!?
However, it is understood that anything a human does is in order to achieve a certain purpose, and the main intention in his/her brain while pursuing that goal should be the outcome and the end result of this pursuit.
And behold regarding the following verse -
In the begining God created the Heaven and Earth
On this the sages teach -
בראשית ברא כְּמוֹ שֶׁדְּרָשׁוּהוּ רַבּוֹתֵינוּ בִּשְׁבִיל הַתּוֹרָה שֶׁנִקְרֵאת רֵאשִׁית דַּרְכּוֹ (משלי ח'), וּבִשְׁבִיל יִשְׂרָאֵל שֶׁנִקְרְאוּ רֵאשִׁית תְּבוּאָתוֹ (ירמיה ב');
בראשית ברא IN THE BEGINNING GOD CREATED — God created the world for the sake of the Torah which is called (Proverbs 8:22) “The beginning (ראשית) of His (God’s) way”, and for the sake of Israel who are called (Jeremiah 2:3) “The beginning (ראשית) of His (God’s) increase’’.
As we see here that at the inception of creation the intentions from the Blessed HaShem was Israel and the Torah, which didn't even come until the end of the Creation, in which case, Esav doesn't have a right to complain about what Jacob took, as this world was created for Israel who delves in the Torah, and since Jacob our forefather was a simple man who sat in peace in his tent studying Torah, then certainly only to him would it be fitting all the goodness of this world. And with this we can understand what Isaac our forefather meant when he said to Esav - 'Your brother came in guile, with wisdom of the Torah', that since the wisdom of the Torah was with Jacob, then certainly all reality is with him, and there really is no claim against him for taking the blessings..
And on this path we can explain the above Medrash -
"A woman who conceives"
That's what is written - [Psalms 139:5] "You have created me behind and before."
The intention here is that even though man was created last, none the less, since the total intention of the creation was simlpy for humanity, it was as if humans were created first. And this is why it is written "You have created me behind and before." That even though humans were created last, none the less it is as if we were fashioned from old, as if we were created before everything, even though we came in last.
Therefor, if one is worthy to be toiling in Torah and keeping her commandments, that person is by default fulfilling his/her purpose, and through this arrives at the purpose of the entire creation which was simply designed for him/her, and then we say on that person, that they were created before the act of creation itself, as all of the creation was created just for him/her, and we know that everything ends in action, but is founded in thought.
And if someone doesn't act in the ways of the Torah, then it would be impossible for him/her to say that the entire world was created for them, and regarding that person, we say that the mosquito preceded him/her, which is the truth, since humans came on the order of creation after the mosquito.
And with this we can understand the continuation of the Medrash - 'Rabbi Yochanan says - if a person is worthy he/she inherits two worlds, this and the next, a person being worthy is one who toils in Torah and commandments, which was the purpose of the creation, and then we inherit the two worlds including this world, since all of this world was only created for humans that dwell in Torah.
And this can explain what is taught in the writings of the sages, that all of creation is included in the following categories -
1. Matter
2. Herbs
3. Animals
4. Humans
And the matter of the earth was made for the grass to grow on it, and the grass for the animals, and the animals for humanity - as we can see that all of these were created for mankind, which is the choice existence of them all. Therefor he/she is considered last, that all actions and processes are for the purpose at the end after all things transpired. However, it is still considered last, and none the less at the same time we see it was there from the start in intention and purpose, and this should be understood.