Your last sentence quoted clearly describes people with inherited wealth. In my opinion, that's not describing a poor person, by almost any measure. It falls into the sibling commenter's category description of petit bourgeoisie.
They borrow it from the extended family, everyone chips in, it's like a risky investment that some day can pay off.
When the extended family funds are not enough, they borrow from the "organized crime", i.e. the narcos.
Sometimes they don't pay the whole sum before and now they own to the coyotes, which are also the narcos.
During the immigration process, they are getting abducted, executed (whole buses of immigrants were killed in Mexico), the rules change midway, usually they own more money at the end that were agreed at the start.
Definitively they are not the petit bourgeoisie.
Some go into debt, hoping there'll be opportunity on the other side of the border. Some lose their lives when they aren't able to pay those debts back to the coyotes.
But, relative poverty in this situation would mean that you don't have your own land, to do this.
Wikipedia comments that subsistence farmers typically have meaningful economic power in their community: https://en.wikipedia.org/wiki/Subsistence_agriculture