Part of the puzzle of this poem comes from the speaker's use of metonymy to refer to everyday things. Metonymy is a way of referring to something by naming something closely associated with it.
The very first word of the poem is "Caxtons," by which the Martian means "books." The Martian uses this term because William Caxton, a 15th-century merchant, diplomat, and writer, introduced the printing press to England and became the first English retailer to sell printed books. So, in a sense, Caxton invented the printed book, and for some unexplained reason, the Martian identifies all books with Caxton's name. Combined with the Martian's description of these "mechanical birds" and their "markings," the term "Caxtons" is enough to identify these objects as books.
Similarly, the Martian uses metonymy when describing cars, opening line 13 with the words "Model T." The Model T was the famous Ford automobile, first produced in 1908, that made car travel affordable for middle-class Americans.
Most readers probably know that the Model T is a type of car, so the Martian's use of metonymy here isn't too puzzling. What's strange, however, is the fact that the Martian knows about the Model T and William Caxton. Where does the Martian get such deep knowledge of human history? Yet the Martian's terminology points also to their unfamiliarity with human life, since no one actually calls books "Caxtons" or cars "Model T." Ultimately, it seems this Martian's knowledge of Earth derives much more from background research than everyday experience!