This is not accurate.
The timeframe is not wrong; it is true that the concept of the modern police, at least in the US, was largely based on the Peelian model created in London in the 1820s. But saying it evolved from "warehouse guards and slave patrols" is ahistorical. Most modern police forces modeled after London's Metropolitan Police replaced night watch systems that have been around for literally all of recorded history.
I'm not saying the night watches didn't evolve into police departments, I'm saying the night watches were co-opted prior to them becoming uniformed departments.
And slave patrols led directly into being police departments in some parts of the US. I do not claim that's in the history of all depts, but across the south there are many cases of patrols becoming formalized into police departments.
For the slave patrol point, I would appreciate a single example of this phenomenon. Is it the claim that there exists at least one professional police force that was created to replace a "slave patrol", which previously performed some subset of the civil duties of police officers? I have not been able to find an example; can you point me to one?
Potter, Gary "The History of Policing in the United States"[1] references Platt, Tony, "Crime and Punishment in the United States: Immediate and Long-Term Reforms from a Marxist Perspective, Crime and Social Justice 18"
1. https://www.academia.edu/30504361/The_History_of_Policing_in...
Should progressive academics declare all CATO papers invalid because they are ideologically misaligned with the institute?