Clearly it says he was in Sheol or Hades in Acts 2:31 which is drawn from a prophetic psalm about Christ.
Psalm 16:10 For You shall not forsake my soul in the unseen; You shall not allow Your benign one to see corruption.
Or in Hebrew
Ki la thozb nphsh'i l'sheol la ththn chsid'k l'rauth schchth
Or in Greek (from the Septuagint)
For you shall not abandon my soul in Hades nor shall you give your sacred one to see corruption.
ὅτι οὐκ ἐγκαταλείψεις τὴν ψυχήν μου εἰς ᾅδην οὐδὲ δώσεις τὸν ὅσιόν σου ἰδεῖν διαφθοράν
Then there is this;
Act 2:27 For Thou wilt not be forsaking my soul in the unseen [Hades], Nor wilt Thou be giving Thy Benign One to be acquainted with decay.
Act 2:27 ὅτι οὐκ ἐγκαταλείψεις τὴν ψυχήν μου εἰς ᾅδου οὐδὲ δώσεις τὸν ὅσιόν σου ἰδεῖν διαφθοράν.
Drawn from Acts 2:22-28, which clearly speaks of Jesus being in the unseen, which is Hades - or Sheol.
Men! Israelites! Hear these words: Jesus, the Nazarene, a Man demonstrated to be from God for you by powerful deeds and miracles and signs, which God does through Him in the midst of you, according as you yourselves are aware - This One, given up in the specific counsel and foreknowledge of God, you, gibbeting by the hand of the lawless, assassinate, Whom God raises, loosing the pangs of death, forasmuch as it was not possible for Him to be held by it. For David is saying to Him, I saw the Lord before me continually, Seeing that He is at my right hand, that I may not be shaken." Therefore gladdened was my heart, And exultant my tongue. Now, still my flesh also shall be tenting in expectation, For Thou wilt not be forsaking my soul in the unseen, Nor wilt Thou be giving Thy Benign One to be acquainted with decay." Thou makest known to me the paths of life. Thou wilt be filling me with gladness with Thy face.
Jesus went for three days down into Hades, Sheol, the Grave. This is what the scriptures say, and this is how the scriptures interpret the "Heart of the Earth" passage. Your interpretation has some merit friend, but it is not the sole foundational Truth of the matter; because Christ entered into Hades, and that is what the scriptures say.
Hades - The Grave, the unseen.