Dust has an important place in the idiom of Hebrew thinking. See the appendix below for the meaning of the word in both its literal and figurative/metaphoric senses.
Note that the figurative sense include several that depict humiliation and self abasement. This is an apt (Hebrew) description for the poor, who by reason of their circumstances, cannot be proud but must be humble.
Some of the listed references (Jonah 3:6, Job 2:8, see also Luke 10:13) also have people who wish to display penitence, "sit in the dust" - another quintessential Hebrew idiom.
1 literally:
a. dry, loose earth, thrown (in malice) 2 Samuel 16:13 ("" אֲבָנִים);
עַלרֿאֹשׁ ׳וַיַעֲלוּ ע Joshua 7:6 (J E; sign of grief), so Ezekiel
27:30; Lamentations 2:10, and (with זָרַק) Job 2:12; loose earth (on
surface of ground) 1 Kings 18:38; Amos 2:7; Micah 1:10; Isaiah 34:7,9;
Leviticus 17:13 (H) Ezekiel 24:7 (in figurative), Numbers 5:17; Job
14:19; Job 38:38; Job 39:14; Genesis 26:15 (R), made into siege works
Habakkuk 1:10; of sand-storm Deuteronomy 28:24 (+ אָבָק); as serpent's
food, token of punishment and humiliation, Genesis 3:14 (J) Isaiah
65:25 (compare Micah 7:17 2e below); ׳זֹחֲלֵי ע Deuteronomy 32:24
(poem; compare 2e).
b. specifically as material of human body Genesis 2:7; Genesis 3:19
(J), Ecclesiastes 3:20, compare Job 4:19; Job 8:19; Psalm 103:14, to
which it returns (שׁוּב אֶלֿ) Genesis 3:19; Job 10:9; Psalm 104:29;
Ecclesiastes 3:20; so (with עַל) Job 34:15; Ecclesiastes 12:7.
c. = surface of ground Exodus 8:12; Exodus 8:13 (twice in verse); (P;
הָאָרַץ ׳ע), Job 19:25; Isaiah 25:12; Isaiah 26:5 (both "" אֶרֶץ),
surface of (whole) earth Job 41:25, ׳מְחִלוֺת ע Isaiah 2:19 (for
hiding), so ׳ע alone Isaiah 2:10, compare ׳חֹרֵי ע Job 30:6; = soil,
Job 5:6; Job 14:8.
d. powder of anything pulverized Deuteronomy 9:21 (twice in verse)
(compare דָּ֑ק "" Exodus 32:20), 2 Kings 23:6 (twice in verse); 2
Kings 23:12,15, so in simile 2 Samuel 22:43 = Psalm 18:43, hence =
ashes Psalm 18:4; Numbers 19:17.
e. debris, of ruined city 1 Kings 20:10; Ezekiel 26:4,12; Nehemiah
3:34; Nehemiah 4:4; Psalm 102:15. The following are late:
f. earth of the grave: אֶשְׁכַּב ׳לֶע Job 7:21, so (with עַל) Job
20:11; Job 21:26, compare Job 17:16; ׳יוֺרְדֵי ע Psalm 22:30,
׳שֹׁכְנֵי ע Isaiah 26:19, ׳יְשֵׁנֵי אַדְמַתעֿ Daniel 12:2; עֲפַרמָֿוֶת
Psalm 22:16; ׳ע in figure Psalm 30:10.
g. mortar (i.e. dried mud) for plastering houses Leviticus 14:41,42,45
(P).
h. (iron-) ore Job 28:2; עַפְרֹת זָהָב Job 28:6 gold-dust (but see
סַמִּיר).
i. material of earth Isaiah 40:12, compare ראֹשׁ עַפְרֹת תֵּבֵל
Proverbs 8:26 the first of the earth particles of the world.
2 figurative:
a. of abundance Genesis 13:16 (twice in verse); Genesis 28:14 (all J)
2 Chronicles 1:9; Job 27:16; Psalm 78:27 ("" חוֺל יַמִּים), compare
עֲפַר יַעֲקֹב Numbers 23:10 (JE); with added idea of commonness,
worthlessness Zephaniah 1:7; Zechariah 9:3.
b. of worthlessness (alone) Job 22:24.
c. simile of the scattered, dispersed 2 Kings 13:7; ׳כֶּע Isaiah 41:2
(so van d. H. Ginsb; Baer ׳כֵּע; on meaning see Du Che, reading
תְּשִׂימֵם for יִתֵּן).
d. of self-abasement Genesis 18:27 (+ אֵפַר), ׳וְנִחַמְתִּי עַלעֿ
וָאֵפֶר Job 42:6, מִּיהוּ ׳יִתֵּן בֶּע Lamentations 3:29.
e. of humiliation (sitting or lying in dust) Isaiah 47:1; compare
Isaiah 29:4 (twice in verse), Job 16:15; Job 40:13; Psalm 7:6; Psalm
44:26; Psalm 119:25, simile Job 30:19; licking dust Psalm 72:9; Isaiah
49:23; Micah 7:17, compare Tel Amarna tikalu ipra (of enemies, see
WklAltor. Forsch. iii. 291; also of serpent 1a above); of ׳י raising
from the dust 1 Samuel 2:8 = Psalm 113:7, 1 Kings 16:2; of lifting
oneself Isaiah 52:2.
