Although "blkfern-jungal" by Aileen Corpus (an example of Black Australian Aboriginal verse) may be slightly difficult to understand at first, it seems that the themes presented are universal, easily discernible if one takes the time to work through the unfamiliar dialect.
A theme is defined as:
...the central and dominating idea in a literary work...In addition, the term means a message or moral implicit in any work of art.
In other words, a theme is a message (or messages) the author is trying to convey to the reader, what I call "life truths." These messages are generally valuable in that the truth being shared is something many people can relate to, despite differences in diverse cultures, ethnicity, etc. It is the universality that makes the piece so enduring. This is certainly the case in Corpus' poem.
A poor black man is on Regent Street, a location he knows well. The people are folks he is familiar with. He notes some other black men who are very well dressed, compared to the speaker who is sitting in the gutter ("gutta").
The narrator notes that they are black, but not so in their connection to their race as much as simply being black:
wlk’n down regent street i see
blks hoo display blknez
(i min they sens of blknez)...
They display "blknez," but these do not see themselves as connected to their roots. In fact, it is perhaps their desire to appear different that suggests a desire to separate themselves from the life the narrator leads.
They infer that they are so much better than our speaker, perhaps because they are able to dress well—putting on an appearance of success. In their "wisdom," they offer empty advice—that time is...
...gonna lif yoo outta
yor blk hole n sho yoo
how t’wlk n dress n tlk.
Their suggestion is that if the narrator waits long enough, time will improve his place in life. The men do not offer ideas or help as to how the man will achieve this. Less concerned with helping, they seem more interested in lording their achievements over this less fortunate man. There is no talk of education; health care; training; or, employment. They talk of the "better life" (as they see it), but not a way to get there. It is a sham.
The narrator looks at their fine clothes and down again at his "soiled blknez." In that moment, he seems to clearly perceive what they are offering him—which is nothing more than the attire and speech of success. I get the sense that the man sees their achievement as nothing more than cleaning up the man—not making the man himself better. The narrator understands that while he may be poor, he is clearly more in touch with what it means to be black.
So he turns their words back at them, saying:
‘ime gonna lif yoo outta
yore blk hole n sho yoo
how t’wlk n dress n tlk’
To me he seems to say that in time, you may be more than you are now, and that the clothes don't matter any more than mimicking the speech of those you associate with "success." He is giving them guidance as to how to be better men: perhaps better black men. The inference may be, also, that clothes and talk promised do not improve lives: that they could learn something from him.
In terms of themes, one cliche is: clothes don't make the man. Another is: you can't judge a book by its cover. And last, a common motif in literature is the difference between reality vs. appearance. Anyone can dress up in nice clothes. But the man is no different unless he changes his inner-person somehow.