The Gault "Clovis" site also has produced artifacts that predate Clovis as have at least two in the Southern Hemisphere. I suppose it is possible to conclude form followed function across a continent creating the same projectile/spear points. The primary argument against that is it never happened again during pre-Columbian North America - even regionally where the same animals were hunted.
I believe the mainstream explanation (not a good one) is that the megafauna Clovis Point was essential for its task and that "only one design" was acceptable. For typical mammals a variety of designs would be acceptable resulting in divergent designs.
I don't like this answer at all, but I believe that is the mainstream explanation.
