We can try to put our feet in their shoes. However, if their is no written traces of their thinking--and even then we would still read it with our modern minds--we may never know the why, if there is a why.

I have a few ideas for writing down an article on it. Again, the most probable answer will just be prospective science without a possibility to prove or reject them.

About your interesting remark, we could also count phalanges+joints+tips of each finger, which means 28 * 28 = 784 🤪 🥵 🥳