(you are not actually going to read all of the evidence anyway, so I am giving it not so much for you, since you will just ignore it, but I am giving it for those who love to study God's word, prayerfully and carefully.... the heart of the earth ...
Again from Strong's: A form of H3824; the heart; also used (figuratively) very widely for the feelings, the will and even the intellect; likewise for the centre of anything: - + care for, comfortably, consent, X considered, courag [-eous], friend [-ly], ([broken-], [hard-], [merry-], [stiff-], [stout-], double) heart ([-ed]), X heed, X I, kindly, midst, mind (-ed), X regard ([-ed)], X themselves, X unawares, understanding, X well, willingly, wisdom.
Thus we can see by Genesis 6:5, in their respective translations/versions, that the word used [“καρδια” [Tr. kardia]/“לבו” [Tr. “labe”]], is associated with other words like “imagination” and “thoughts”.
* (so-called), the LXX [Septuagint] is not the work of 70 Jewish scholars, and not written before AD 100, but is the work of the gnostic Origen in his Hexapla.
In Matthew 13:15 KJB, citing, Isaiah 6:10 KJB, the people did not want to “understand” with “their heart”. This again confirms the [Alpha; [so-called (LXX)]] Genesis use, and further if we turn to last [Omega] use of this form of the Greek word, in Revelation 18:7 GNT-TR, we see the words connected as, “she saith in her heart”.
Other uses/forms are also connected with the “spirit” - Psalms 51:10,17 of a man, and as such as that “he thinketh in his heart, so is he” - Proverbs 23:7, etc.
For the many uses of the word G2588 [καρδια] in the (so-called) LXX, see [minus the Apocrypha]:
“Genesis 6:5, 20:5,6; Exodus 25:2, 31:6, 35:5,10, 36:2; Deuteronomy 6:6, 8:2,5,14,17, 9:4, 15:9,10, 18:21, 19:6, 20:8, 28:47, 29:18, 30:14, 32:46; JoshuaB 2:11, 23:14; JudgesA 19:22; 1 Kings 1:13, 2:35, 7:3, 9:19, 12:20,24, 21:13, 27:1, 29:10; 2 Kings 6:16, 7:3, 18:14; 3 Kings 2:4, 8:23,48,66, 10:2,24, 12:26; 4 Kings 10:30,31, 20:3, 23:3,25; 1 Chronicles 28:9, 29:9; 2 Chronicles 1:11, 6:14,38, 7:10, 9:23, 13:7, 16:9, 19:9, 22:9, 25:2, 29:31, 32:31, 34:31, 35:19b; 1 Esdras 1:21; 2 Esdras 7:10,27; Esther 1:1l, ... Psalms 7:11, 9:2,27,32,34, 10:2, 11:3, 12:3, 13:1, 14:2, 23:4, 31:11, 35:11, 36:14,31, 39:11, 44:6, 52:2, 57:3, 61:5, 63:11, 65:18, 72:1, 73:8, 75:6, 83:6, 85:12, 89:12, 93:15,19, 94:10, 96:11, 100:5, 108:16, 110:1, 118:2,10,11,34,58,69,145, 124:4, 137:1, 139:3; ... Proverbs 3:5, 4:21, 6:14, 10:8,22, 12:20, 13:12, 14:33, 18:4, 19:3,21, 20:5, 23:34, 26:24, 28:26, ... Job 22:22, 33:23, 36:13, 37:24, 38:2, ... Psalm of Solomon 1:3, 8:3; Hosea 7:2; Obadiah 1:3; Zephaniah 2:15; Isaiah 6:10, 9:8, 38:3, 44:18,19, 46:8, 47:7,8,10, 49:21, 51:7, 57:1, 60:5, 61:1; Jeremiah 5:24, 7:31, 12:11, 13:22, 19:5, 23:26, 36:13, 39:41; Ezekiel 6:9, 27:4, 27:25,26,27, 28:2,8, 44:7,9, ...”
Other forms of the same Koine Greek word, may be seen here -
Kata Biblon Wiki Lexicon - καρδία - heart (n.)
H3820 - lēḇ - Strong's Hebrew Lexicon (kjv)