Israel is a people, not a person.
As I said, your speech gives you away, for I know you are not a Jew practicisng Judaism, for no Jew would ever say such a thing as you have said, for they know the origin of the name itself:
Gen_32:28 And he said, Thy name shall be called no more Jacob, but Israel: for as a prince hast thou power with God and with men, and hast prevailed.
Gen_32:32 Therefore the children of Israel eat not of the sinew which shrank, which is upon the hollow of the thigh, unto this day: because he touched the hollow of Jacob's thigh in the sinew that shrank.
Gen_35:10 And God said unto him, Thy name is Jacob: thy name shall not be called any more Jacob, but Israel shall be thy name: and he called his name Israel.
"Israel" is a spiritual name (meaning "prince/ruler/overcomer with God", see John 16:33; Revelation 3:21), given for victory over sin, to a single man, who was a "type" of the real Israel (a single person, a man) to come:
Hos 11:1 When Israel was a child, then I loved him, and called my son out of Egypt.
Notice, "Israel" is a single "child", an "him", even specifically "my [God's] son". Matthew, under inspiration of the Holy Ghost, in Matthew 2:13-15,19-21, citing Hosea 11:1, says that Jesus is the actual fulfillment of Hosea 11:1:
Mat 2:15 And was there until the death of Herod: that it might be fulfilled which was spoken of the Lord by the prophet, saying, Out of Egypt have I called my son.
Jacob of old, the single person who was given the name, was therefore, not the fulfillment in full, but only in shadow, in type, in example pointing to the reality to come, as Jesus has said:
Joh_5:39 Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me.
Luk_24:27 And beginning at Moses and all the prophets, he expounded unto them in all the scriptures the things concerning himself.
It was Jesus, the real "Israel" who overcame all temptation to sin by the strength of His Father, by and through the Holy Ghost. Jesus wrestled in the garden and won.
Just as Jesus is the real
"Adam" (1 Corinthians 15:44-46).
Just as Jesus is the real
"David" (Jeremiah 30:9; Ezekiel 34:23-24, 37:24-25; Hosea 3:5).
etc.
Christians are therefore the "children
of Israel (Jesus)" (Hebrews 2:13; Isaiah 8:16,18; John 13:33) and thus are real "Israel of God" (Galatians 6:16), which are not the children after the flesh of Jacob (Romans 9:8), which are not really "of Israel". Jesus is the true Israel into which persons are grafted, the real stock.
Don't know why you are quoting Ecclesiastes.
Yes, I know why you don't know why.
Ecclesiastes, written by Solomon under inspiration of the Holy Ghost, speaking of the entire "duty" of mankind (all in Adam) towards God:
Ecc 12:13 Let us hear
the conclusion of the whole matter:
Fear God, and keep his commandments: for this is
the whole duty of man (the Adam).
Ecc 12:13 HOT šôf Dävär haKol nish'mä et-häélohiym y'rä w'et-mitz'wotäyw sh'môr Kiy-zeh Käl-häädäm
Ecc 12:14 For God shall bring every work into judgment, with every secret thing, whether it be good, or whether it be evil.
Jesus Christ is the true Adam, 1 Corinthians 15:44-46.
"The Sabbath" was "made" for "the man" (Mark 2:27-28).
The only "the man" in Genesis is Adam, of which things were "made" for.
Colossians 1:16 states that in reality all things were "made" "for" Jesus, who is "the man" (1 Timothy 2:5)
We are to obey those commandments which are for us. Jews have one set, Gentiles have a different set.
You are greatly mistaken, as Ecclesiastes states that keeping God's commandments (Ten Commandments) are every man's (of mankind, of Adam, first or last) duty.
Exo_12:49 One law shall be to him that is homeborn, and unto the stranger that sojourneth among you.
The peoples Israel of old were to be the light to the entire world that was in gross darkness, taking the glorious light of the commandments of God to all:
Pro_6:23 For the commandment is a lamp; and the law is light; and reproofs of instruction are the way of life:
Deu 4:5 Behold, I have taught you statutes and judgments, even as the LORD my God commanded me, that ye should do so in the land whither ye go to possess it.
Deu 4:6 Keep therefore and do them; for this is your wisdom and your understanding in the sight of the nations, which shall hear all these statutes, and say, Surely this great nation is a wise and understanding people.
Deu 4:7 For what nation is there so great, who hath God so nigh unto them, as the LORD our God is in all things that we call upon him for?
Deu 4:8 And what nation is there so great, that hath statutes and judgments so righteous as all this law, which I set before you this day?
Isa_60:1 Arise, shine; for thy light is come, and the glory of the LORD is risen upon thee.
Luk_2:32 A light to lighten the Gentiles, and the glory of thy people Israel.
As Jesus said:
Mar_12:24 And Jesus answering said unto them, Do ye not therefore err, because ye know not the scriptures, neither the power of God?