Inventions vs Ideas
It can be confusing when we try to attribute an 'invention' to Leonardo when we don't know if he actually constructed it, or simply drew a doodle of an idea, or an intention. Does it matter? Maybe, maybe not. We give credit (patents) to people before they have a working model - based on an idea alone, but there is a semantics problem with the word "invention" since it is usually used to denote building something rather than the idea of it. After all someone could say "I have an idea for an anti gravity space ship" but you wouldn't really say they "invented" it - would you? But, if they were the first person to ever actually even imagine such a thing - that is also significant. It's interesting to note that someone can be the first to have an idea but then not be able to bring it to fruition or to make it work - so the ideation of something - that person can be different from the person who constructs a working model and it's debatable which is more difficult. The inception of an original idea - creativity - or the practical application or engineering of it.
We usually use 'inventor' as a way to combine the original idea of something and the development and the actual manifestation of a working model or at least a proof of concept. With Leonardo we dont' usually know if he actually built something, or had more detailed drawings, or even if he was the source of the idea itself. Just because he wrote it down or drew it - doesn't mean the idea came from him - it's that most other people at the time didn't write anything down and if they did it wasn't preserved. It could be that someone else inspired an idea for something - and he took it further or expounded on it.
So when we refer to many of Leonardo's inventions we really mean that he knew of, had a concept of, or envisioned an idea or an invention before anyone else known. That does not mean he was the first in history to ever imagine building a machine to enable man to fly and definitely wasn't the first to imagine flying - any child in history who saw a bird thought about flying and stories of iccaris which predate Leonardo are proof of this. What we mean with the idea for flight was that he used mathematically/ scientific means to envision how to construct a device that would enable a man to actually lift of the ground mechanically rather than "make wings and flap hard" or "magically/ without explanation" Leonardo documented and thought of the actual wind/ shape of the wings/ how it could be propelled and stuff like that. When we say that he "invented the helicopter" we mean that he conceived of the idea that a spinning device could provide lift for a device that could lift a man from the ground. He used wood and fabric in his designs and they probably could not provide enough lift with those materials and man power but the concept / the innate idea of "twisting horizontal propellers" and the actual idea of "lift" and aero dynamics and thermo dynamics were in his mind.
It could have easily been that Leonardo would beaten The Wright Brothers for the first known human flight had been able to work on the idea further. It's definitely not that he was not capable of actually building one that would work - but more so that the time he lived in and his environment didn't facilitate it - but actually hindered it. The Wright brothers were considered crazy enough so you could imagine how someone 500 yeasr before that would have been treated. They were actively burning people at the stake for even speaking such things - let alone physically building something. He existed at a time where you didn't worry about what people thought because it hurt your feelings and confidence but rather than they would literally kill you for being too "weird".
In the same vein we also have to consider Leonardo's ideas that were not tangible or 'inventions' in nature that you could build but intangible - like the idea of gravity, the properties of light, evolution and things of that nature. Einstein is considered the inventor or originator of the theory of Relativity - but that, similar to the Wright Brothers invention of flight - does not mean he was the first in the history of humanity to have considered the idea. He was the first to demonstrate it in a way that could be tested and proven. Perhaps a more apparent example is the theory of gravity or evolution - Darwin and Newton were definitely not the first humans to consider such things or even to develop the ideas to the same extent but again - lack of evidence does not mean it didn't happen. Consider how Darwin's idea was accepted at the time and apply that x1000 to Leonardo's time (and before) and it's easy to understand that even if Leonardo (or others) considered such things that they could not express them in any kind of obvious or apparent way. Leonardo conceived of the Telescope before Galileo (100 years before) and he was put on house arrest for the rest of his life - so he wasn't really the 'first' but just who is known to be the first.
When we say that Leonardo had the idea or the conception for certain areas or subjects it's likely he had these ideas taken to much more sophisticated forms in his mind - which couldn't be written down. Not to mention the lack of actual words to express such things as. Consider also that Newton, Darwin, Einstein - while consider the first to consider their "inventions' didn't actually 'create' something but rather discovered or notice something that was already there and was there long before they existed or thought of them. These ideas could have already been understood or considered long before they did - but just didn't make it to history, or did but were lost. The Library of Alexandria could have had detailed accounts of these concepts or maybe there are still things buried that will push back the timelines for such things even before Leonardo's time.
Consider also that these type of ideas are very abstract and dont' really - didn't really have any practical significance and the majority of people didn't have the time or desire to sit around and wonder why some animals look similar to each other or how many bones they have in their hand is mathematically proportional to the wrist and arm as a whole. Does it matter why an apple falls? Literacy was almost non-existent let alone scientific literacy which wasn't even a subject but more a gift that each recipient of which had to develop on their own by the circumstances and environment in their own life time .
After all how can you learn something when there is no one alive who knows about it? That is what ideation or creativity are - generating ideas or concepts without being told. That doesn't mean you have to be the first, or that you created it, but rather that you had the ability to REALIZE something that already exists - is there and attempt to understand it in a more elaborate and intentional matter.
Articles will explore the ideas and concepts present in Leonardo's work - extracting such things from his notebooks and works of art and attempting to almost play a game of pictonary from 500 years ago. Some of these may seem "out there" or that we are reading too much into something but you have to consider the source and that he is considered the smartest human to have ever lived - and that anything we can understand today - and that exists perpetually (ideas) could have been not only understood by him during his life time but perpetuated and envisioned into areas that most today cannot even conceive of.
You have to be able to imagine that he as able to imagine anything you could - so if you think that you're seeing a design for a space ship - its likely exactly that. It also doesn't mean he built one any more than Gene Roddenberry did.