The political leadership of Brazil have constantly rejected any form of restrictions and still do. If you knew that Bolsonaro and Trump had something of a buddy club, that would tell you a lot.
But you also have to understand that there are many things going on here.
There is exceptional poverty in Brazil - many people have no access to clean water, and no ability to isolate. People have to go to work - unless you are amongst the fortunate middle classes, the vast majority must go to work, and the poorest often have to travel significant distances using public transport to get to where they work.
Some areas, like Manaus, are still significant travel hubs for vast swathes of the area, and loggers etc., are constantly flowing in and out .Not just from other areas of Brazil, but from other parts of the world. And one has to bear in mind that a fair few of the workers in the Amazon are involved in illegal activities including illegal logging and land clearance. There is some evidence that some of those have been deliberately involved in infecting indigenous peoples - one tribe recently lost its last male (in a patrilineal society where the tribe ceases to exist if there are no men) to Covid.
And whilst there is a public healthcare system, in large parts of Brazil it is centred around smaller hospitals and clinics which have a restricted level of services mainly within mainstream practices - significant levels of ICU and specialised services have never been needed so they do not exist.
Brazil is not remotely like the UK.