@joro.jur The advice being given here is hard-earned knowledge through the School of Hard Knocks (experience). The reason @Puddy, @'RZL, and @FrieChamp are saying to scale back on what you are trying to accomplish is because we can tell that you are underestimating the complexities of a single project, if not multiple projects simultaneously. To contextualize why this is so difficult, look at Valve. Presumably their company structure is set-up to be flat and allows employees to work on whatever project(s) their heart desires. How many new innovations does Valve produce? How many new products, IP's, services, etc . . . Not that many. The reasons for this are a great multitude ranging from interest levels, fatigue, to turnover in personnel and lack of clear direction due to flat management styles.
To clarify, it is like trying to spread too little butter across too much bread. The covering of butter is not adequate to provide a tasty treat on any portion of the bread. Whereas if you use a smaller piece of bread, the butter fully covers the bread. Do not assume you will have more butter because resources are always finite, particularly when first starting.
I would also reiterate what @Puddy had said about expecting people who likely work full-time and have some years of experience working on hobby projects. They are projects of passion, but time is not limitless. If I only have X amount of time in a day, and I intend to devote 1 year to a hobby project, then my full effort should go into that single project and not be split between others so that I maximize the output (result). So you are better served to scale back what you want to do, be specific, give a time frame to work on it (e.g., 1 year), and be receptive to feedback. Furthermore, as a 15 year old you are going to struggle to find people willing to work with you. That's the reality. So again, scaling back and demonstrating knowledge, experience, and understanding of scope will increase the likelihood that you are successful.
No one is saying a 15 year old cannot do it, but we are saying to tread cautiously and understand that you are attempting to be a project manager, which encompasses a great depth and breadth of knowledge. Read, a lot, on what others have accomplished and how they did it. There is no perfect model, but recognizing your own limitations is critical to being a good manager.