Shared ground
These lines widen Psalm 148’s “praise” roster to include the land and the life on it: terrain (“mountains and all hills”), vegetation (“fruit trees and all cedars”), and animals (“wild animals and all cattle,” plus “small creatures and flying birds”). The repeated “all” signals that the poet is not picking a few scenic examples but is aiming at total inclusion within each category.
The text explicitly treats non-human creation as being addressed like a worshiping audience. At minimum, that is poetic speech that lets a human community speak as if the whole world were joining in.
Where interpretation differs
One difference is how literally to take creation “praising.” Some read it mainly as figurative language: the world “praises” by existing as God made it and by displaying God’s power and beauty. Others think the language points to a real, if mysterious, participation of creation in honoring its maker (not with human words, but in a fitting creaturely way).
A smaller difference is what “small creatures” refers to. It can be heard as reptiles, insects, or generally “things that move close to the ground.” The verse itself doesn’t narrow it further.
Why the disagreement exists
The passage is a hymn with direct address to non-human things, which naturally pushes readers to ask what kind of “speech” or “response” the poet intends. Also, the animal term translated “small creatures” is broad enough that translations and readers make slightly different choices.
What this passage clearly contributes
These verses reinforce a creation-wide vision of God’s worthiness: not only humans, but the entire earth—its heights and low places, its cultivated and uncultivated life, its big and small animals, and even the air filled with birds—is portrayed as belonging in a single chorus. The pairs (mountains/hills; fruit trees/cedars; wild/tame; ground/air) add up to a picture of comprehensive scope rather than a narrow slice of nature. See the continuation into human society in Psalm 148:11.
