The poem is intentionally simple, to sound almost like regular conversation. There are times when it deviates from conventional conversation-like syntax though.
Syntax is how the words are arranged in a sentence. The poem is arranged in rhyming lines (including the half rhyme of “home” and “come” in lines 5-6). To get such perfect rhymes, and the iambic tetrameter, you are going to need to vary from conventional speech.
Line 4 is an example of changed syntax.
And home we brought you shoulder-high.
Normally, we would say: “We brought you home shoulder-high” but that would not have the right rhythm (even though it maintains the meter). In line 7, we see the same thing for the same reason.
And set you at your threshold down.
In line 19-20 the syntax differs both to keep the meter and to keep the rhyme.
Runners whom renown outran
And the name died before the man
So you can see that sometimes poets have to use words creatively in order to maintain the structure and the rhythm they want. The iambic tetrameter gives the poem a sing-song, almost chanting quality that is very haunting.