But does it matter because of the species of wood, or because like people no 2 trees are the same even if they are the same species?
Have you ever looked at a pallet of 2x4's at a hardware? The variation is unbelievable, especially on the cheap non structural stuff. And it's all pine, and probably all came from exactly the same location.
Both and all of the above.
Species - yes, and I believe you can assign some VERY general characteristics to different species - this one is brighter than this one, and this one is darker than this one... But within any given species, like people, no two are going to e the same, and it is totally dependent on that particular piece of wood.
I think the mass of the neck - as in how much actual wood is there - is very impactful on tone, especially considering how much of the string is vibrating over the neck. I also think the number of pieces used to construct the body has a big impact. Something that is often missed in the debate about "are more expensive instruments worth it" is how many pieces of wood are used to make a body. A fender MIM bass might be made from three, four, or five unique pieces of wood glued up together. Maybe those 5 pieces really work together to make beautiful tone, but when you buy a more expensive bass, you are likely getting one, maybe two pieces.
I also think that there are some very talented people out there, with lifetimes of experience building instruments, who probably play, touch, and listened to more instruments in any given week than any of us can hope to in our lifetimes. I don't think the worlds best master luthiers are all coordinating with each other and pulling off some kind of massive scheme to defraud the people of the world regarding wood and tone.
Granted, it may be as much of an art as it is a science, but when those guys knock on body blanks, and put tuning forks to them, they are seeing how the wood resonates - it's not a fake show they are putting on for the benefit of selling a bass to your for a few grand more.