Two things.
1. Lev 19:18 You shall not take vengeance, nor bear any grudge against the children of your people, but you shall love your neighbor as yourself: I am the Lord.
>>Is the idea of loving your neighbor new to the NT? No... he was repeating an existing commandment. Which leads to...
2. The word for "new" is kainos which means "new in regards to freshness, renewed." The word "neos" is "new in regards to AGE, i.e. brand new. But kainos is more like renewed... made fresh.
Thus, messiah took a commandment that already existed and revealed the depth behind it... made it fresh.
Just because an English translation says "new" doesn't mean it is brand new, David.
Blessings.
Ken
If you are citing Strong's it has been found to have about 15,000 errors and omissions. Here is the definition of "Kainos" from Bauer, Danker, Arndt, Gingrich one of, if not the, most highly accredited Greek lexicons available.
καινός, ή, όν (Aeschyl., Hdt.+; ins, pap, LXX, TestSol; TestAbr A 7 p. 84, 27 [Stone p. 16]; Test12Patr; JosAs 14:13 and 15; Philo, Joseph., Just., Mel.) comp. καινότερος; prim. sense ‘new’.
① pert. to being in existence for a relatively short time, new, unused (X., Hell. 3, 4, 28; PGM 36, 265; Judg 15:13; 2 Km 6:3; 4 Km 2:20) ἀσκοί wineskins (Josh 9:13) Mt 9:17; Mk 2:22; Lk 5:38. ἱμάτιον (Artem. 2, 3 p. 86, 3; 3 Km 11:29f) vs. 36. μνημεῖον Mt 27:60; J 19:41 (w. ἐν ᾧ οὐδέπω οὐδεὶς ἦν τεθειμένος added). τὸ κ. the new piece=πλήρωμα Mk 2:21; Lk 5:36. καινὰ καὶ παλαιά Mt 13:52 (perh. with ref. to coins; cp. PGrenf II, 74, 9; 77, 7f).
② pert. to being not previously present, unknown, strange, remarkable, also w. the connotation of the marvelous or unheard-of (Pla., Apol. 24c; X., Mem. 1, 1, 1 ἕτερα καὶ καινὰ δαιμόνια; Just., A I, 15, 9; Orig., C. Cels. 1, 58, 15) διδαχή Mk 1:27; Ac 17:19. ἐντολή (κ. νόμος: Menand., Fgm. 238, 3 Kö.; Diod S 13, 34, 6) J 13:34; 1J 2:7f (Polyaenus 2, 1, 13 οὐ καινοὺς νόμους … ἀλλὰ τ. παλαιούς); 2J 5. ὄνομα (Is 62:2; 65:15) Rv 2:17 (here w. ὃ οὐδεὶς οἶδεν εἰ μὴ ὁ λαμβάνων, perh. as antidote to adversarial magic); 3:12. ᾠδή 5:9 (Ps 143:9; cp. Is 42:10; Ps 32:3; 39:4.—Philo, Vi. Cont. 80 ὕμνος κ. [opp. ἀρχαῖος]); 14:3. γλῶσσαι Mk 16:17. κ. γένος of Christians Dg 1. θεώρημα AcPl Ox 6, 1f (διήγημα Aa I, 241, 11). θέαμα GJs 19:2f (Mel., P. 19, 127). Christ as ὁ κ. ἄνθρωπος the new kind of human being IEph 20:1. ἢ λέγειν τι ἢ ἀκούειν τι καινότερον either to hear or to say someth. quite new (=‘the latest thing’) Ac 17:21 (s. Kühner-G. II 306f; Norden, Agn. Th. 333ff [but s. HAlmqvist, Plutarch u. d. NT ’46, 79f, w. ref. to Plut.]; B-D-F §244, 2; Rdm. 70 and s. Demosth. 4, 10 ὦ ἄνδρες Ἀθηναῖοι … λέγεταί τι καινόν; γένοιτʼ ἄν τι καινότερον … ; also Theophr., Char. 8, 2; BGU 821, 6 [II A.D.] ὅταν ᾖ τι καινότερον, εὐθέως σοι δηλώσω; Simplicius, Coroll. De Tempore, in Aristot., Phys. p. 788, 36ff καινοτέραν ἐβάδισεν ὁδόν=he traveled a rather new road [of interpretation]; Jos., Ant. 14, 104; Iren. 1, 18, 1 [Harv. I 169, 3]).
③ pert. to that which is recent in contrast to someth. old, new
ⓐ w. no criticism of the old implied (Herodas 4, 57 καινὴ Ἀθηναίη; Lucian, M. Peregr. 12 κ. Σωκράτης): of the Son of God or Logos, who is old and new at the same time Hs 9, 12, 1ff; Dg 11:4.
ⓑ in the sense that what is old has become obsolete, and should be replaced by what is new. In such a case the new is, as a rule, superior in kind to the old ἡ κ. διαθήκη the new covenant or declaration (Jer 38:31; Just., D. 11, 4 al.; Did., Gen. 46, 4; 156, 5) Mt 26:28 v.l.; Mk 14:24 v.l.; Lk 22:20; 1 Cor 11:25; 2 Cor 3:6; Hb 8:8 (Jer 38:31), 13; 9:15. κ. νόμος (Timocles Com. [IV B.C.] Fgm. 32, 4 κατὰ τὸν νόμον τ. καινόν; Just., D. 12, 3; Mel., P. 7, 46) B 2:6. λαὸς κ. 5:7; 7:5; cp. 15:7.—Esp. in eschatol. usage κ. οὐρανοί, κ. γῆ (Is 65:17; 66:22) 2 Pt 3:13; Rv 21:1; Ἰερουσαλὴμ καινή vs. 2; 3:12. καινὰ πάντα ποιεῖν 21:5. καινὸν πίνειν τὸ γένημα τῆς ἀμπέλου Mt 26:29; Mk 14:25.—Of the renewing of a pers. who has been converted κ. ἄνθρωπος Eph 4:24; Dg 2:1. κ. κτίσις a new creature 2 Cor 5:17a; cp. 17b (Ps.-Pla., Axioch. 11 p. 370e ἐκ τῆς ἀσθενείας ἐμαυτὸν συνείλεγμαι καὶ γέγονα καινός=out of weakness I have brought myself together and become new; cp. Orig., C. Cels. 6, 67, 33); Gal 6:15; cp. B 16:8. All the Christians together appear as κ. ἄνθρωπος Eph 2:15.—RHarrisville, The Concept of Newness in the NT, ’60; GSchneider, Καινὴ Κτίσις (Paul and background), diss. Trier, ’59, Neuschöpfung oder Wiederkehr? ’61. Qumran: DSwanson, A Covenant Just Like Jacob’s, The Covenant of 11QT 29 and Jeremiah’s New Covenant: New Qumran Texts and Studies, ed. GBrooke/FMartínez ’94, 273–86.—B. 957. Schmidt, Syn. II 94–123. DELG. M-M. EDNT. TW. S. νεό.
Arndt, W., Danker, F. W., Bauer, W., & Gingrich, F. W. (2000). A Greek-English lexicon of the New Testament and other early Christian literature (3rd ed., pp. 496–497). Chicago: University of Chicago Press.