I think a good analogy here OP is like saying you want to be an artist when you haven't been painting and developing a unique style all of your life.
You won't get an agent without a showreel, but a showreel needs to include acting work you secured on merit not on being on the books of an extras agency.
You don't know how it feels on stage, how you look on camera, how a set works, how contracts work, how you are at learning scripts super quickly and efficiently, what the job titles of everyone in a theatre production or tv crew mean etc.
And yes everybody has to start somewhere but you're probably 15-20 years behind the people you'll be competing with.
Drama schools require auditions not just sign up. If you haven't done amdram before, only extras work, I would assume you want to be famous rather than having an absolute and raging passion for acting. Because if you had that then you would have experience by now. And if you don't have experience because you only recently decided you want to be an actor then you aren't cut out for it, that lifelong passion would have called you to such a difficult and risky vocation in life already.
I think it's incredibly unfair of you to call people bitter when they are giving constructive advice from within an incredibly competitive industry. You asked for help and you're getting it, it's just not what you want to hear.
Re which roles you look at and think you could do, at this stage you really don't know because you haven't been acting but doing extras work. So you haven't found your lane and really actors should be able to turn their hand to any role or at least be willing to do this for a long long time at the beginning of their career.
As others have asked, what is your motivation for becoming an actor and most importantly would you be happy to work in call centre / bars etc for minimum wage for your working life if it means you get to give this your best shot?