directory structure

when i install ci4 using composer, it creates the struture shown below. I presume my app goes in the top level app so whats the reason for vendor/codeigniter/framework/app and the other duplicates? can i delete the duplicates (keeping the system of course)?
thanks, Bill
app
........config
........controllers
public
tests
vendor
........bin
........codeigniter4
................framework
........................app
................................config
................................controllers
........................public
........................system
........................tests
........................writable
........composer
........fakerphp
........ad nauseum
writable