Two Dozen 18th Century Coffins

While building an apartment building in Philadelphia’s historic district in 2017, construction workers unearthed two dozen intact coffins and human remains. Experts dated the remains, belonging to over 60 individuals, to the 18th century. The site is believed to be a decommissioned burial ground for the First Baptist Church, established in 1707. When the church relocated to a larger location in 1860, all remains should have been transferred to the Mount Moriah Cemetery. How or why these were left behind is unknown.
I'm wondering, if s/o writes:
"Faaaake - how can it be?
The US exist since 1776-07-04 ! Nothing can be before!
Don't be a woke leftist, do your own research, touch some grass and never trust science or the universities!"
Bomb! What the fuck?