Why is the information available to archeologists about early Native American culture very limited?

Early Native Americans had no written language, since they passed down their history orally-so they have no written history of early Native Americans.

Cause of limited information on Native Americans:

The European invasion caused a lot of problems other than battles and colonialism in Native America. The disease destroyed the Native American culture before it could be documented. Among other things that ensued included the introduction of diseases that killed 90% of Americans.

The Americans had their fair share of diseases but the outbreak of influenza, typhus, fever, smallpox and etc. following invasion exasperated the catastrophic death. Other than diseases everything that came with the Europeans diluted the rich culture.

Hence, the lack of archaeology records of the Native Americans. Animals, seeds, weeds, etc., altered the social landscape.