Yes, I agree. However, mention of the afterlife is present in the Hebrew Scriptures. For instance, Gabriel tells Daniel, "But as for you, go your way to the end; then you will enter into rest and rise again for your allotted portion at the end of the age.” Daniel 12:13
And if I think about it, the promise you quoted from Deuteronomy invites the reader to speculate as to why God's promises are multigenerational. God makes promises to some people who will never see their fulfillment in their lifetime. Only those who love God and put trust in his faithfulness will find such prophecies to be interesting. For instance, God promised Abraham that he would be the father of many nations. And though God didn't fulfill that promise in Abraham's lifetime, Abraham believed God anyway.
Very good observation, my brother.
The idea Jews had about afterlife was more a collective view, as a nation. They were more concerned about their descendants, the generations to come, more than in the fate of their individual soul in the Sehol.
Resurrection (and the fate of individual soul) started to be a concern or religious concept, after contact with Zoroastrianism during the exile in Babylon. That's why the book of Daniel contains that reference you mention. Jews who returned to Israel to rebuild Jerusalem brought with them ideas like heaven, hell, angels, demons, Satan, Final Judgement and Resurrection, as interpreted by Zoroastrian priests of the time plus their own adaptation of those concepts to Judaism. Then came the Greeks with their particular conceptions of soul.
By the time of Jesus, some Jews believed in a physical, literal resurrection (following the teachings of the Pharisees) and some not (following the teachings of the Saducees). The kind of resurrection that Pharisees believed in was so literal, it seems, that led to the question of who would "own" a woman who had been married to different men. They thought not only that people resurrected in flesh, but in mind and with all societal characteristics. To me, the wise answer of Jesus points out to the spiritual meaning of the resurrection, but that would perhaps be the subject of other thread.