The Torah doesn't begin with "God spoke to Moses saying:..." because Moses didn't need to exist according to the Torah. The Torah does not seem to take for granted that everything that happens was intended to happen. Somethings are definitely foreshadowed and prophecies are given, but that isn't true for everything.
Case in point is Ishmael. God clearly tells Abraham that he'll have a son, and so Isaac and his descendants are definitely part of "the plan." However, it seems to me that Ishmael wasn't a part of "the plan," and instead became something that God has to work around because Sarah and Abraham were trying to make the prophecy of Abraham having a son come true by introducing Hagar into the mix. But if Sarah and Abraham had just continued to wait and not had Hagar become a concubine, then so many things would have happened so differently and God even has to kind of correct Abraham's expectations or ideas about Ishmael because it's a deviation from the plan.
On that same vein I don't believe it was destined for Moses to exist or for Israel to need a human redeemer. Perhaps if Joseph's family hadn't have had so much infighting, attempted murders, and deceit to the bitter end then things with the famine and Egypt could have played out differently. I also don't recall any prophecy or foreshadowing of a great redeemer taking Abraham's descendants out of Egypt, but instead that they would be enslaved for centuries and God would punish the Egyptians and set the Israelites free, with no mention of a Moses type figure.
ד וְהִנֵּה דְבַר-יְהוָה אֵלָיו לֵאמֹר, לֹא יִירָשְׁךָ זֶה: כִּי-אִם
אֲשֶׁר יֵצֵא מִמֵּעֶיךָ, הוּא יִירָשֶׁךָ. 4 And, behold, the word of
the LORD came unto him, saying: 'This man shall not be thine heir; but
he that shall come forth out of thine own bowels shall be thine heir.'
ה וַיּוֹצֵא אֹתוֹ הַחוּצָה, וַיֹּאמֶר הַבֶּט-נָא הַשָּׁמַיְמָה
וּסְפֹר הַכּוֹכָבִים--אִם-תּוּכַל, לִסְפֹּר אֹתָם; וַיֹּאמֶר לוֹ, כֹּה
יִהְיֶה זַרְעֶךָ. 5 And He brought him forth abroad, and said: 'Look
now toward heaven, and count the stars, if thou be able to count
them'; and He said unto him: 'So shall thy seed be.' ו וְהֶאֱמִן,
בַּיהוָה; וַיַּחְשְׁבֶהָ לּוֹ, צְדָקָה. 6 And he believed in the
LORD; and He counted it to him for righteousness. ז וַיֹּאמֶר,
אֵלָיו: אֲנִי יְהוָה, אֲשֶׁר הוֹצֵאתִיךָ מֵאוּר כַּשְׂדִּים--לָתֶת
לְךָ אֶת-הָאָרֶץ הַזֹּאת, לְרִשְׁתָּהּ. 7 And He said unto him: 'I am
the LORD that brought thee out of Ur of the Chaldees, to give thee
this land to inherit it.' ח וַיֹּאמַר: אֲדֹנָי יְהוִה, בַּמָּה אֵדַע
כִּי אִירָשֶׁנָּה. 8 And he said: 'O Lord GOD, whereby shall I know
that I shall inherit it?' ט וַיֹּאמֶר אֵלָיו, קְחָה לִי עֶגְלָה
מְשֻׁלֶּשֶׁת, וְעֵז מְשֻׁלֶּשֶׁת, וְאַיִל מְשֻׁלָּשׁ; וְתֹר, וְגוֹזָל.
9 And He said unto him: 'Take Me a heifer of three years old, and a
she-goat of three years old, and a ram of three years old, and a
turtle-dove, and a young pigeon.' י וַיִּקַּח-לוֹ אֶת-כָּל-אֵלֶּה,
וַיְבַתֵּר אֹתָם בַּתָּוֶךְ, וַיִּתֵּן אִישׁ-בִּתְרוֹ, לִקְרַאת
רֵעֵהוּ; וְאֶת-הַצִּפֹּר, לֹא בָתָר. 10 And he took him all these,
and divided them in the midst, and laid each half over against the
other; but the birds divided he not. יא וַיֵּרֶד הָעַיִט,
עַל-הַפְּגָרִים; וַיַּשֵּׁב אֹתָם, אַבְרָם. 11 And the birds of prey
came down upon the carcasses, and Abram drove them away. יב וַיְהִי
הַשֶּׁמֶשׁ לָבוֹא, וְתַרְדֵּמָה נָפְלָה עַל-אַבְרָם; וְהִנֵּה אֵימָה
חֲשֵׁכָה גְדֹלָה, נֹפֶלֶת עָלָיו. 12 And it came to pass, that, when
the sun was going down, a deep sleep fell upon Abram; and, lo, a
dread, even a great darkness, fell upon him. יג וַיֹּאמֶר לְאַבְרָם,
יָדֹעַ תֵּדַע כִּי-גֵר יִהְיֶה זַרְעֲךָ בְּאֶרֶץ לֹא לָהֶם,
וַעֲבָדוּם, וְעִנּוּ אֹתָם--אַרְבַּע מֵאוֹת, שָׁנָה. 13 And He said
unto Abram: 'Know of a surety that thy seed shall be a stranger in a
land that is not theirs, and shall serve them; and they shall afflict
them four hundred years; יד וְגַם אֶת-הַגּוֹי אֲשֶׁר יַעֲבֹדוּ, דָּן
אָנֹכִי; וְאַחֲרֵי-כֵן יֵצְאוּ, בִּרְכֻשׁ גָּדוֹל. 14 and also that
nation, whom they shall serve, will I judge; and afterward shall they
come out with great substance.