As a general rule, upon the death of an individual any life insurance proceeds, bank accounts, mutual funds and retirement distributions pass to a named beneficiary and pass outside of the Estate. Usually, the a person would sets up a beneficiary on these accounts and this allows for that person or persons to receive funds directly without the necessity of probate. creditors cannot attach to these proceeds because they do not pass through the probate process.
However, when there are no named beneficiaries or successor beneficiaries the funds may be distributed directly to the estate of the deceased individual. In which case an estate would be have to be open and funds would be part of the Estate.