On the first day of the week, a psalm for David. The earth is the Lord's and the fulness thereof: the world, and all they that dwell therein. For he hath founded it upon the seas; and hath prepared it upon the rivers. Who shall ascend into the mountain of the Lord: or who shall stand in his holy place?
Psalms 23:1 On the first day of the week, a psalm for David. The earth is the Lord's and the fulness thereof: the world, and all they that dwell therein.
Psalms 23:2 For he hath founded it upon the seas; and hath prepared it upon the rivers.
Psalms 23:3 Who shall ascend into the mountain of the Lord: or who shall stand in his holy place?
Psalms 23:4 The innocent in hands, and clean of heart, who hath not taken his soul in vain, nor sworn deceitfully to his neighbour.
Psalms 23:5 He shall receive a blessing from the Lord, and mercy from God his Saviour.
The verse centers on "world", "first", "week", "psalm", "david", "earth", "lord's", and "fulness". It is saying that the verse draws attention to "world" and "first", so its meaning should be read from those terms before moving to application.
The next verse adds "The innocent in hands and clean of...", so "world" and "first" should be read forward into that movement. In The LORD as Shepherd, the local focus is trust, covenant mercy, guidance, and worship.
A plain takeaway is to answer the verse's own emphasis on "world" and "first" with trust shaped by these words, not by a vague optimism outside the passage.