Gosh you need legal advice.
If the insurance was payable to, say, the wife on the death of the deceased, then the payout is the wife's asset. It is not, and never was, a part of the estate of the deceased, and so none of it can be claimed by the creditors.
In an ideal world, probate would have been granted, and accounts produced and signed off appropriately, so that creditors could see the insolvency of the estate, and then negotiations made so that if there was any estate left over after legal and funeral costs, that should have been divided proportionately between the creditors. If the estate could not cover legal and funeral costs, the creditors should have been shown accounts to prove this, and then they would write off the amounts owed
All this is assuming debts are solely in the name of the deceased. Any shared debts are of course immediately the liability of the person who is still alive to resolve.
As there has not been probate, and presumably, no legally signed off record of accounts created, the whole thing is a mess. A lawyer should be consulted to see what can be done retrospectively to tidy this whole thing up.
Also worth noting, a person can legally decline executorship, which can force a court to appoint an executor. Can be a good option with insolvent estates depending on the appetite of those involved.