Most niche communities from R*ddit are pretty much dead here unless you are looking forward to being a regular poster yourself. This rather requires sticking to the lemmy.world open feed rather than creating a custom feed with your communities only, if you are looking to scroll a lot instead, of course. Just stick around a bit, see how often what communities and people reach the general feed, elect to block the ones that feel flooding your feed or not to your taste. Maybe give some regularly-posted communities that are previously not in your area of interest some chance before going on a mass block. This place does have a quality and rather genuine people, but in a limited scope.