I see Nick has already welcomed you here, a good move.
Having a sh*t job is pretty terrible, but the way you think about yourself in relation to it really is a mistake (sorry to be blunt).
If you had a great well paid interesting job the made you want to be there all the time it is true you would be happy, however hte amount of effort and strength of character to go to work would be pretty minimal.
Dealing wiht the grind and unfairness of a boring low paid job wiht poor conditions is a hard task, and by doing it one is worthy of respect and to be admired.
Feeling you are helpless and pathetic is silly. You had nothing to do with the economic situation, the number of people fighting for too few jobs, or the fact that many businesses pay as low as they possibly can -and don't care about their workers. You do not set the pace at work, so if you have trouble keeping up then you are not being looked after.
Trying to cope in these conditions does take technique. Do you think there is any way you can set up boundaries between the rest of your life and work, so that as soon as your shift is over you mind goes to more pleasant things? Even a podcast or similar on your phone when you get it fixed can put you in a different world.
There are bosses out there that value someone who can deal with your sort of situation, they are not all exploitative. While the vacancies ads are all going to be targeted by everyone have you considered maybe doing a bit of volunteering, often the way to a job in itself?
Living at home can be both good and bad, can I ask how you get on there?
If you are worried about getting depressed or having anxiety how would you feel about going to a doctor to be assessed? Many will bulk-bill, so if you book a long appointment you should be able to make a start at explaining things.
I hope to hear more from you