Primary highway classification is reserved for major arterial roads or highways that connect other significant population centers. Secondary at highest is what I would classify some of these roads, but a lot of very minor roads like dead-end streets were tagged as primary so I was caught off-guard and confused. It's good to observe the surrounding area to see how everything else is classified or read into what you're working with before changing the classification of roads, as how roads are classified on the map can affect the routing of OSM-based navigation systems or simply be a rendering eyesore.