Every gift, conveyance, assignment, transfer, or charge that is not upon consideration deemed valuable in law, or that is upon consideration of marriage by an insolvent transferor or by a transferor who is thereby rendered insolvent, shall be void as to creditors whose debts were contracted at the time such gift, conveyance, assignment, transfer, or charge was made but shall not, on that account merely, be void as to creditors whose debts have been contracted, or as to purchasers who have purchased, after such gift, conveyance, assignment, transfer, or charge was made. Even though it is decreed to be void as to a prior creditor, because voluntary or upon consideration of marriage, it shall not, for that cause, be decreed to be void as to subsequent creditors or purchasers.