Adam -Abraham - Moses - Jesus

Adam sinned/transgressed heavens law long before the Mosaic/covenant at Sinai was cut.

The Mosaic covenant was cut/established with one nation only, Israel. Their purpose was to be a set apart nation of priests/mediators between God & mankind (Ex 19:6). The Sinai covenant was a marriage contract (Isa 54) between God & ALL on Sinai that willingly agreed (Ex 19:8).

Even though on many occasions the people failed & were ultimately divorced by the Lord (Jer 3:8). Their overall purpose was a success, in as much as, the old/now obsolete Mosaic law covenant was mankind's teacher (Gal 3:24-26) that all are sinners.

Heavens required wage/price/payment owed for sin (even 1, Ja 2:10) is, DEATH (Rom 6:23)

NT Post-conversion/salvation: ALL Past-Present-Future are sins, Forgiven! (Rom 8:1, 1 Jn 2:12, Eph 1:7, 4:32, Col 3:13, Heb 9:12, 10:14, 13:20 to name a few)

This doesn't mean post New covenant conversion/salvation, sin never carries a consequence. Having said that, loss of salvation isn't one on those consequence (1 Cor 3:15).

Consequence from sinning post-conversion/salvation could manifest itself, in many different ways. A health issue, a broken relationship, prison, disease, lost heavenly rewards earned etc.

There is only 1 unforgivable sin = lack of Faith/REJECTING Christ's sin atoning sacrifice & resurrection.

Good works & obedience are the evidence of your Faith not the cause of your salvation.

Rom 1:5 "Through him we received grace" & apostleship "to call all the Gentiles to the obedience" "that comes from faith" for his name’s sake.
(MY NOTE: Faith in Jesus sin atoning work & resurrection lead to our obedience, for HIS Name's sake)

Rom 16:26 but now revealed and made known through the prophetic writings by the command of the eternal God, "so that all the Gentiles might come to the obedience" "that comes from faith"
(MY NOTE: Thru our Faith in Jesus sin atoning work & resurrection. Christ's Gift of the indwelling Holy Spirit will lead us obedient/godly behavior.)

Act 3:25 Unto you first God, having raised up his Son Jesus, sent him to bless you, in turning away every one of you from his iniquities.
(NOTE: It's Faith in the risen Christ's sin atonement. That frees believers from sins grip & enables them to repent/turn from their sin)

Rom 2:4 Or despisest thou the riches "of his goodness" and forbearance and longsuffering; not knowing that "the goodness of God leadeth thee to repentance"?
(NOTE: It's thru the GOODNESS of GOD not thru OUR OWN great work of sin repentance, obedience or self-control. That we REPENT/change our thinking/course. It's salvations seal of indwelling Holy Spirit that leads us to REPENT/change our thinking outlook & direction).

1 Jn 1:8 If we say that we have no sin, we deceive ourselves, and the truth is not in us.
(NOTE: Anyone that believes they can conquer their own sin nature, without Gods help is mistaken)

When believers make salvation's focus about their sin, good works or lack thereof. They take the focus off of Christ, His work, what He did at Calvary.

All praise, glory & honor belong to our Lord/God & Savior, Jesus the Christ!

The New Better eternal blood covenant (Heb 13:20) that our Risen High Priest/Christ mediates is tied to the promise/covenant the LORD made to Abraham 430 years before Sinai (Gen 12 & 15).

Rom 4:13 For the promise, that he should be the heir of the world, was not to Abraham, or to his seed, through the law, but through the righteousness of faith.
(MY NOTE: God's heir promise to Abraham was the righteousness obtained/accessed thru faith, not righteousness obtained/accessed thru law keeping)

BTW: The paradise that OT believers went to is called Abrahams bosom (Lk 16:19-31, not Moses) The marriage feast set in heaven, is at Abrahams table (Matt 8:11, not Moses). Not to take anything away from Moses, scripture proclaims Moses was a faithful servant of the Lord. (Num 12:7, Heb 3:5)

Finally:
1 Cor 15:
1 Moreover, brethren, "I declare unto you the gospel which I preached unto you", which also ye have received, and wherein ye stand;
(NOTE: Scripture declares the gospel which Paul preached to believers. (See 1 Cor 1:2)

2 "By which also ye are saved", if ye keep in memory what I preached unto you, unless ye have believed in vain.
(NOTE: The gospel of Salvation, Paul preached. (See next 2 verses)

3 For I delivered unto you first of all that which I also received, how "that Christ died for our sins" according to the scriptures;
(NOTE: Christ died for our sins)

4 And "that he was buried, and that he rose again the third day" according to the scriptures:
(NOTE: Christ was buried & he rose again the third day. Also see Rom 10:9-10, Eph 2:8, Col 1:14)

Gospel of Christ Recap: "The gospel of Salvation" IS "Christ died for our sins was buried & rose again the third day")

Gal 1:
7 Which is not another; but there be some that trouble you, and would pervert the gospel of Christ.
(MY NOTE: The gospel of Christ. (Reread 1 Cor 15:1-4)

8 But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed.
(MY NOTE: The NT gospel of Christ isn't adherence to the Mosaic sacrificial law system)

9 As we said before, so say I now again, if any man preach any other gospel unto you than that ye have received, let him be accursed.
(MY NOTE: Any preaching other then gospel of Christ received/accessed thru Faith, not works brings a curse)

I believe anyone that places adherence to anything other then FAITH placed in Jesus sin atoning work & salvation is/will be accursed/anathema.

Was it for Israel or for mankind?

It's my view: The Sinai covenant was cut with Israel only. They were to be a light to the world: Isa 42:6, 49:6, 51:4, Lk 2:32, Acts 13:47.

During the Feast of Sukkot/Tabernacles (Num 11 & 29) also known as the Feast of Nations. 70 bulls were sacrificed 1 for each nation (Gen 10). And finally in the kingdom to come, all nations will travel to Jerusalem to worship the King (Zec 14:16).

I was just curious as to how you can say that the Law was for Israel only, but then say it was for "mankind."

Was that just a mistake to say that the Law was for mankind? Gentiles are of "mankind," and so were those of the Seven Nations.

Here's what I said: The nation (Ex 19:6) was set apart for a work. To be priests = mediators between God & mankind.

In my reply to your question I said this: They were to be a light to the world/mankind: Isa 42:6, 49:6, 51:4, Lk 2:32, Acts 13:47.

Additional help"
Rom 5:12 Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned:
(MY NOTE: Adam's sin against heavenly law. Passed the DEATH sentence onto all mankind!)

OP states aprox 2500 yrs before the establishment of the Mosaic law covenant (Israel only) cut at Sinai. Adam transgressed/sinned against (already existing) heavenly law.

Under the new covenant that begins after Christ pays heavens required price for sin/DEATH (Mosaic covenant ends right here). After Jesus resurrection & the establishment of the new covenant (1st post resurrection Pentecost) Anyone that accesses Jesus payment (His sin atoning death & resurrection) thru Faith. Live under Christ's NT laws of LOVE. God 1st & your brother.

Anyone that places their Faith in Jesus sin payment receives a full SIN pardon & eternal life in the presents of there creator Lord/God & Savior, Jesus the Christ.

To Christ be all praise, glory & honor. Amen

The verses below support my view that gentiles were never under Mosaic (Israel only) covenant laws.

Eph 2:11 Wherefore remember, that ye being in time past Gentiles in the flesh, who are called Uncircumcision by that which is called the Circumcision in the flesh made by hands;
(MY NOTE: Circumcision: A blood covenant made with hands & required under Mosaic law)

Eph 2:12 That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world:
(MY NOTE: Gentiles referred to as the Uncircumcision (vs 11) were without God, having no covenant promises & a hopeless future)

Eph 2:13 But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ.
(MY NOTE: But, NOW! = Post death & resurrection/New Melchizedek priesthood sin management covenant/system. Believing gentiles are no longer bastards living outside of covenant seals)

Rom 2:14 For when the Gentiles, which have not the law, do by nature the things contained in the law, these, having not the law, are a law unto themselves
(MY NOTE: Gentiles were never under/never part of the Mosaic law covenant cut a Sinai)

Council at Jerusalem 51 AD
Acts 15:1 And certain men which came down from Judaea taught the brethren, and said, Except ye be circumcised after the manner of Moses, ye cannot be saved.
(MY NOTE: Jews try to place gentiles under Mosaic covenant laws)

Acts 15:23 And they wrote letters by them after this manner; The apostles and elders and brethren send greeting unto the brethren which are of the Gentiles in Antioch and Syria and Cilicia.
(NOTE: The apostles send letters to gentile Christ believing churches in Antioch, Syria & Cilicia.)

Acts 15:24 Forasmuch as we have heard, that certain which went out from us have troubled you with words, subverting your souls, saying, Ye must be circumcised, and keep the law: to whom we gave no such commandment:
(NOTE: The letters sent by Christ chosen apostles. Proclaim that gentiles, are not, nor were they ever, required to be circumcised or keep Mosaic law. Quoting: WE gave NO such commandment!)

Lastly I said, 70 nations when referencing Gen 10. God chose ONE nation/Israel to be the light/reveal HIM to the other 69 gentile nations/mankind.

You are absolutely right! I misread your words! Sorry!