How to get carteira de trabalho if I can't get RNE

You can't get a Labor Card without a CRNM, which is what the old CIE/RNE is called now.
A job offer will let you get a CRNM and a Labor Card, but only if your prospective employer applies to the Labor Ministry and gets approval in advance to hire you:  an informal job offer won't do you any good.
If you become a student in a recognized course, including a recognized course in the Portuguese Language, you can qualify for a student visa -- but you're not allowed to do paid work on a student visa, and so you can't get a Labor Card.
If you're here on a visitor's visa, I'm not aware of any easy way that you can extend your stay beyond the limit of that visa, much less work legally.

what are the documents that i have to present to the Labor Ministry? I have a prospective employer.

You don't have any documents to file with the Labor Ministry directly:  your employer needs to contact them, and file an application on your behalf.   The Ministry will inform them of the required documents, which can vary depending on the job.

Got it. Thank you for the help!

All the best to you.
Unfortunately, many Brazilian employers will say, "Oh, sure, I'll give you a job!", then get cold feet when they have to justify it to the Labor Ministry.   Hope that you're luckier.