The idea is salvation had not reached its completion during their lifetime. Their salvation wasn't complete until Christ's sacrificial death, what was promised.
The term completed Jew emphasizes this meaning. The Old Testament (Tanakh) is incomplete without (apart from) the New Testament (New Covenant). The Old Testament saints looked forward to the Messiah, even as early as Moses (Deut. 18:15-19). Even for the Orthodox Jew, who does not accept Jesus Christ as the Messiah, sees the need for the Messiah yet to come.
Appendix -- References
Now if perfection [τελείωσις] had been attainable through the Levitical priesthood (for under it the people received the law), what further need would there have been for another priest to arise after the order of Melchizedek, rather than one named after the order of Aaron?
(Heb. 7:11, ESV)
For Christ is the end [τέλος] of the law for righteousness to everyone who believes.
(Rom. 10:4, ESV)
τελειόω ... ① to complete an activity, complete, bring to an end, finish, accomplish ...
② to overcome or supplant an imperfect state of things by one that is free fr. objection, bring to an end, bring to its goal/accomplishment ... ③ As a term of mystery religions consecrate, initiate, pass. be consecrated, become ...
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Arndt, W., Danker, F. W., Bauer, W., & Gingrich, F. W. (2000). In A Greek-English lexicon of the New Testament and other early Christian literature (3rd ed., p. 996). University of Chicago Press.
That apart from us they should not be made perfect (ἱνα μη χωρις ἡμων τελειωθωσιν [hina mē chōris hēmōn teleiōthōsin]). Negative purpose clause with ἱνα μη [hina mē] and the first aorist passive subjunctive of τελειοω [teleioō]. But this glorious and gracious purpose (foresight) of God is not due to any special merit in us. It is simply the fulness of the time in God’s dispensation of grace of which we are the beneficiaries.
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Robertson, A. T. (1933). Word Pictures in the New Testament (Heb 11:40). Broadman Press.
11:40. “Made perfect” here refers to the consummation of salvation (1:14), the resurrection of the dead (11:35). All the righteous would be raised together at the very end of the age (Dan 12:2, 13).
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Keener, C. S. (1993). The IVP Bible background commentary: New Testament (Heb 11:40). InterVarsity Press.
Nevertheless, on the other hand, these heroes of faith, even though they kept on trusting, did not receive what had been promised in their own lifetimes (v. 13), because God had planned something better, namely, something that would involve us who came later; so that only with us would they be brought to the goal (or “perfected, made complete,” as explained in 7:11, Ro 10:4N). God’s secret plan for history (Ro 11:25–26, 16:25–26; Ep 1:9, 3:9), involving the perfecting of human beings from all times, places and cultures (Rv 7:9–10), Gentiles as well as Jews (Ro 11:25–36; Ep 1:9–14, 2:1–3:11), is glorious beyond imagining (Ro 11:33–36, Ep 3:20–21). Only by trusting God can anyone enjoy its benefits.
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Stern, D. H. (1996). Jewish New Testament Commentary : a companion volume to the Jewish New Testament (electronic ed., Heb 11:39). Jewish New Testament Publications.