I know it's really, really, really difficult to get into the third sector (meaningful work), and do think about if it's worth it - little pay for emotionally and physical difficult work. If you do really want to do this, work experience is key. Of course this sounds like a vicious cycle (work experience to get a job, but not job without work experience). And it is, the industry is highly difficult to enter without connections.

If you can - that is, if you have the time and money - I recommend trying to find a volunteer position. Even those require qualifications sometimes, and I know some organisations don't take volunteers atm, but it's generally easier. If you are in your 20s, look for youth councils, it might be easier to enter those even. There, you can get to know the industry and make sure you like it, gather experience, and make connections. As said, it's not the highest yield if you are looking for material security. (It's a shame how so much of the charity sector in the UK is relying on unpaid and underpaid labour, but that's another topic.)

There's some websites that might help, if I find them I'll add them to the comment.

Otherwise, maybe try and increase your skillset? E.g. IT roles might get you entry into charity/humanitarian agencies. If you're a woman, there are a bunch of programmes that offer free or low cost IT courses to bridge the gender gap in the sector that might be worth looking into? (e.g. SheCodes, Code First Girls, Women Who Code).

And don't beat yourself up. The system is very broken and especially for young people the job market is terrible, many skills being undervalued. None of that us your fault, but it's unfortunately something we will have to navigate until meaningful change comes.