Asking about what skills you need and what the building blocks are etc, the answer is the same - you need to practice and do proper training. We can't just tell you how to be an accomplished actor on this thread in the same way we can't teach you how to drive. You need to practice and / or train depending on your outcome.
The question is - what is the actual training and does it 'work' for those with no natural instinct.
Driving is not the same as that is a very teachable skill as it has no unquantifable 'art' to it (not talking about professional racing driver. If someone asked could someone with no natural ability become a good driver and if so how, the answer would be -
Yes.
The first step would be to get some lessons. They will teach you things like -
safety checks before you start the car; how to turn on the car; how to move the car forward, how to brake, how to indicate safely to other users your intended moves, and so. Then once you have those building blocks you will need to get lots of practice and this is best done on quite roads until you get your confidence and so forth. Then take a test. Then after that you can do an advanced driving course.
You start with the training (but the issue is what form does the training take and what can it teach you first) and then practice.
Suggesting just going to am-dram groups is like saying just go and have a go at driving without knowing what you are doing.
There are so many variables and without more details I am not quite sure what you are asking OP. If you could be less cryptic people might be able to offer targeted advice? E.g. do you wish to train, and get an agent an work professionally? How old are you? Do you work or are you a student? Could you train full time? What is your acting experience so far? Do you have any non-professional credits? Do you have a showreel?
None of this is relevant because it isn't about being a professional actor or having a show reel. It is just a theoretical question about can you take a person with no natural ability (or instinct - someone who at the start would be actively 'bad') and teach them to act well or does it require some charisma/spark natural talent.
It is really weird the way some posters are focussed on the why/what/who aspect of a theoretical question. It's like someone asking 'do you think you could teach someone with no talent and no experience to be a good artist ?' and getting the responses well how old are you, do you have a portfolio, have you painted before. That question can be answered yes because painting and drawing is very formulaic and you start with learning to draw which can be taught, light and shade, etc etc. You would need to have a professional teacher and then practice but these are the types of things that you learn (list)
To answer the questions you have asked:
E.g. do you wish to train, and get an agent an work professionally? No. It is a theoretical quesiton. It is not about me. I do not want to work professionally. It is not about anyone working professionally. It is just about skill attainment for the sake of skill attainment.
How old are you? Not relevant because it's not about me it's about whether its teachable but for the purposes of the question assume a person a bit older so looking at pure 'skill teaching' rather than a more malleable 'learn on the job' child actor. Say for the sake of argument someone about 30 - a formed adult out of student life. Or even younger 21 even - but I think with very young children making them do something can give a level of skill inherently from 'learning on the job' and that's not what I'm asking about. My question is about teaching acting to a not good beginner cold from scratch.
Do you work or are you a student? Could you train full time? ????
Assume someone willing to train and with the time available to do that either full time or part time. Again this just isn't relevant to the basic question of whether the skill is learnable BECAUSE IT IS NOT ABOUT ME. It's like saying 'can you teach someone French' and answering 'well it could you do it full time or are you working?'. It's irrelevant because that's about the time available to learn and NOT the question which is can it be taught.
What is your acting experience so far? Not about me. I would have thought it was clear that I was talking about an absolute beginner. I suppose given the comments above about building blocks, assume someone who has tried once or twice and was bad/no natural talent so that's how we know.
Do you have any non-professional credits? Do you have a showreel?
The questions is about an absolute beginner with no experience (save to the extent required some evidence that they are bad/no natural talent).