I suspect that all three hypothesis you gave might be true, on one plane or another.
Here are my beliefs, though "beliefs" is a strong word, because actually I do not really know. These "beliefs" are what I tend to think about tarot, but I admit that I am not sure. I will use "beliefs" for lack of a better word.
I believe that tarot is a wonderful psychological took that taps into the archetypal representations of our collective memory.
I believe that most of the time, the querent knows the answers they seek, on a deep unconcious level - even if they do not realise that they know. So tarot (or pendulum, or other type of divination) is a way to tap into this unconcious inside knowledge, and to bring it to the concious surface.
I also believe that synchronicity is a thing : the right card will show up when you need to see it. Especially if you put the intention of obtaining an answer (I think that intention is very powerful - to the point where you have to beware what you wish for !)
One thing I do not believe, is that tarot can predict the future. Because I do not think that the future is set in stone ; it is the fruit of many things that we have no control over, and also of our actions and intentions that we do have control over. At the very least we can change our actions and intentions, we have that free will ; and that can influence the future.
The energies of people and events can lead the future into a certain direction, and tarot can give insight about the direction it takes ; but it is still possible to act upon this chain of event, it is still possible to change the energies involved, therefore IMO it is possible to change the future - so the future cannot be foretold.
In a way, the act of asking the cards for advice is already a way to influence the future.
For the rest, I am actually fond of rationality and I am a sceptic, but I am also open minded and I realise that I have to accept the fact that I DO NOT KNOW.
I try to keep in mind that many times, things have a rational explanation, while also accepting that sometimes they might not.
For example :
When cards are flying all over the place when I shuffle a deck, I do not take much notice of it if it is a deck with sleek cardstock that is notoriously slippery to handle. I am more prone to take notice of a flying card when there is no obvious reason for it to fly in the first place.
Or, when I see something strange from the side of my eye, I remember that my peripheric vision is not great so it is probably my eyes that play optical tricks on me. My friend who is used to seeing entities, tell me that it might be ghosts or entities that I see ; and maybe she is right : I do not know.
I do not know for sure how tarot works.
Empirically I see that tarot has helped me in the past, so it is enough for me to trust that it will continue to help me in the future.
But, even if it is just a psychological tool, it is a great one.
And, I am glad to collect decks just for the sake of how beautiful they are - some decks are wonderful collections of 78 works of art ! So, even if just for that, tarot is worth it.