The word ‘anaw, “humble” or “meek” is used 13x in the Psalter. It refers to a social position; it’s not only, or even primarily, an attitude of mind, but a life-condition. The meek are the afflicted, low-born, abused.
Within the Psalter the word forms a story-arc of sorts.
Early on, the Psalmist assures the humble that the Lord hears and remembers them (Psalm 9:12, 18; 10:12, 17).
The Lord promises food (Psalm 22:26) and joy (34:2; cf. 69:32).
At 37:11, the Lord does more than promise relief from affliction. The meek will “inherit the land” and take delight in the abundance of peace. After that, the accent is on the Lord’s rescue of the humble (76:9), which climaxes in the promise that the meek will be exalted and glorified (147:6; 149:4).
Jesus was simply fulfilling the law and the prophets when he pronounced beatitude on the meek who will inherit the earth.