Every arrowhead I have ever found or come across in person just seems very very dull and blunt. How did the arrowheads penetrate animals such as a mammoths skin? How were they able to use these to fight off foreign invaders and other tribes? These blunt arrows seem like they would do pretty minimal damage with just a standard recurve bow. Was it all up to just a good placed shot? Or were these early humans able to make some pretty heavy drawn bows?
The answer is dependent on quite a bit, especially time period. Stone projectile points on arrows were usually very sharp. Brittle silicon dioxide containing materials like flint, chert, and quartz will fracture in a conchoidal manner creating razor thin edge, though because of it's glass like brittle nature, over time can easily round off. Many cutting tools besides projectile points were made in a similar fashion including knives, drill bits, and scrapers which are often misidentified as arrowheads. Some arrowheads were also made to be blunt, intended to cause trauma on small game or birds.
Projectile point technology also changed over time. During the late ice age, larger spears were commonly employed by people we now refer to as Folsom or Clovis people in North America. Hunting was a group effort on the larger mammals that existed at that time. Spears could be powerfully thrown with an atlatl which extended the users arm length thus leveraging the spears or darts to much greater velocities and distances.
As the bow came to replace the atlatl the spears and darts shrank in size, thus so did the points. Early conquistadors in Florida remarked that they could not fully draw an indigenous bow, which in Native hands could fire arrows that could penetrate their thin metal armor. They must have had close to 70-100 pound draw weight.