...I felt it was more perseverance and blind luck than true skill and mastership/ability in composition/composing.
You may seek knowledge, but don't speak lightly of luck and perseverance - they will be the truest friends on your journey as an artist!
I want to learn things like music theory and etc. but from not any single or specific instrument. Not saying I want to be able to play every instrument, but I want the knowledge to have the potential to.
The way to learn things from no single perspective is to learn them from many perspectives.
I just don't know where to start. Do I just buy any instrument and start there?
I can't imagine many people being able to successfully learn an instrument as their first instrument without actually having a reasonable desire and passion to achieve some level of proficiency on that instrument; although it might be an unhelpful suggestion, actually finding some of that desire within yourself might be helpful!
I do agree with Tim's suggestion of the piano or keyboard, though - its layout is a reflection of the way most common music notation and terminology works.
Start looking up books/resources/etc. on music theory and/or notations per specific instruments and continue along?
Yes. As you journey along, you may find that some instruments and music genres have different theory 'cultures', and talk about things in a different way. Much of music theory as a whole is the collection of these genre-specific ideas and instrument-specific perspectives. There are some bits of theory that are more widely-applicable than others, but the only bits of theory that apply to all music are those that have one foot in physics or psychoacoustics.
I feel like I need some musician insight here to lead me on the right path to musical mastery.
The only advice I'm qualified to give is: don't be like me, flitting from one activity to the next without really taking any of them seriously! I guess try to do the opposite:
- Find something specific that you passionately want to achieve or create
- try to achieve/create it (taking note of the theory that you need to learn in order to do so, given that that is a focus for you)
- if you manage to do so great - find another goal! If not, reassess your goals and your methods and... find another goal!
There is an enormous amount to learn in the musical universe and it can't all be done in one lifetime. It's like travelling the world - you can't go everywhere, but you can do your best to choose the places you do visit.