Why did most ancient great armies have swords, arrows, spears, chariots, etc.?

Question

Did they copy from each other, or were these developed independently? And how come china and japan have same weapons when they never met western powers until early modern period? Even native american indians have arrows when first discovered by europeans. And thats only talking of weapons, what about utensils, farming, clothing, medicine, concept of king, etc. Is there a universal or basic knowledge that is held by people whereever they are?

Answer 1

Some things were developed independently. Native Americans had long bows and arriving Spanish preferred armor piercing cross bows. An invading army captured the weaponry of the conquered. Clubs were pretty universal though they varied from tomahawks to maces.

Answer 2

I suppose civilization developed from a particular area or region and people of that area or region slowly migrated to other places of the globe for the purpose of business or other reasons and started living there (this might have occurred some thousands of years ago) . The weapons were invented in that particular area or region were well known to the migrated people. That is the reason why we find similar type of weapons almost all over the globe.