My apologies if I get this wrong. Is this stating that the many possibilities are all coexisting and that our brain is acting as a filter to provide a view of possibilities that we define as ourselves?

That depends on what you mean by "this". If by "this" you mean MWI (the Multiple Worlds Interpretation of quantum mechanics) then:

> Is this stating that the many possibilities are all coexisting

Yes.

> and that our brain is acting as a filter to provide a view of possibilities that we define as ourselves?

No, your brain is not "acting as a filter". There are multiple "your brains" all "coexisting" in multiple universes (which MWI-ers call "the multiverse"), none of which can ever communicate with each other.