When you cast a creature spell it enters the battlefield from the stack, not the graveyard, hand, exile, or whichever zone it originated from. For a card to enter from the graveyard you need to use a spell or effect that moves the card. The first example in Magic is Resurrection which is a sorcery that says:
Return target creature card from your graveyard to the battlefield.
Some creatures also do it themselves like Bloodsoaked Champion
{1}{B}: Return Bloodsoaked Champion from your graveyard to the battlefield. Activate only if you attacked this turn.
Generally cards that will give you a free equip with Dredging Claw have this phrase "from your graveyard to the battlefield", but maybe some effects are more complex and use different templating.
