There are three "main categories", I shall name them so now, which are of course common, uncommon and rare. When building a deck, you have to have enough cards from each category.
The main filter for these is the filter which contains the rarities, common, uncommon and rare. You can specify, what kind of cards you want with the other filters (For example undead, holy, etc). But if you only have the necessary filter on, which concludes the rarities, by scrolling sidewards you should see all cards.
Btw, forgive me if I made no sense.
E: The rarity filter is automaticly on common.