The first weapon ever used by humans was probably a blunt instrument such as a short stick or a bone.
It would have been something that was to hand.
We adopt the same approach and train with sticks because they can be replaced by any suitable object you might find.

The ancient wandering taoist carried only a staff with them for protection.
A simple stick is an ideal weapon for a tai chi person to use.
It is simple, practical and defensive in nature.

What is most notable is the effect.
Internal power is surprisingly powerful with the effect far outweighing the cause.

Some neigong are ‘doings’, others are not.

The more advanced a person becomes at tai chi, the more powerful the neigong.
Each quality is built upon the preceding ones and is only possible because of what the body can already do.
Clearly the first neigong are very simple.